Big block Chevrolet 330 CC rectangular port 
Big block Chevrolet 330 CC as cast heads for flat tappet or hydraulic roller cam are                                                              $1600.00 a pair     
Intake valve size 2.25” exhaust valve size 1.88”
Intake port volume 330 CC Combustion chamber volume 121 CC.
Mill .006 flat or .010 angle mill per approx 1 CC volume reduction. Head bolt/studs are for AFR heads. Bolts – ARP# 135-3605 Studs – ARP# 235-4106
Verify threads are not too long or short to give correct clamping/torque to engine block.
Use Fel-Pro 1017-1 on Mark IV block or equivalent head gasket.
Note, if using these heads on a Gen V or IV Block you will need to use head gasket for the later model block to prevent over heating. Fel-Pro 1047, Cometec C5434 or equivalent. Intake gasket: MRG 121 or equivalent.
Use thread sealer if head bolt holes in block inter the water jacket. Torque in circular fashion per engine manufactures spec. Torque rocker stud to 45 ft lbs. Use sealer on rocker studs that protrude into intake port. If adjustable guide plate option has been purchased position guide plates so they land the rocker arm in the center of the valve stem. Tighten guide plate center clamp screw to 20 in pounds.
Check pushrods for correct length Exhaust ports are raised .300". Alternator bracket hole located above the exhaust port is raised as well. The bracket will need to be modified to use this bolt hole.
Spark plug recommendations: 3/4 reach 14mm thread
Race          NGK R5671-7 4091 hottest      Street NGK FR4
                     NGK R5671-84554                                    NGK FR5
                     NGK R5671-95238
                     NGK R5671-105820 coldest
Torque heads to 70 lbs or manufacture recommendation. Use hardened washer under head bolt/stud. Use ARP thread lube on bolt threads and under head bolt head and washer.
Re-torque after several heat cycles. Break one bolt loose at a time and re-torque to bolt/stud spec. Rocker studs torque to 45lbs.
Always check piston to head clearance as well as piston to valve clearance. If you run a large dome piston it may be necessary to index the spark plug gap to be pointing down to avoid hitting the piston dome. If ground strap is too close use copper index spacer washers to obtain proper clearance.
If using high lift roller cam springs. Use exhaust rocker stud that the base stud will reach all the way into the bottom hole such as: ARP 235-7203 or ARP 235-7206
Cylinder head flow information
Valve lift    .1      .2      .3      .4      .5      .6      .7
Intake        88    150   228  295   339   357   367
Exhaust    79    128    155  186    220   228   236
Test conducted at 28" of water on Superflow 300 Bore Size:
4.5 " intake 3/4" radius plate . No pipe

                                                                  Bruco Performance

        Big block Chevrolet 305 CC oval port as cast heads with flat tappet or                                                      hydraulic roller  spring setup $1600.00 a pair

Intake valve size 2.25” exhaust valve size 1.88”
Intake port volume 305 CC.
Combustion chamber volume 121 CC
Mill .006 flat or .010 angle mill per approx 1 CC volume reduction.
Head bolt/studs are for AFR heads. Bolts – ARP# 135-3603 Studs – ARP# 235-4103. head bolts are available from Bruco Performance as well. Verify threads are not too long or short to give correct clamping/torque to engine block.
Use Fel-Pro 10171 or equivalent head gasket. Needs 4.5" bore size.
Note, if using these heads on a Gen V or IV Block you will need to use head gasket for the later model block to prevent over heating. Fel-Pro 1047 or equivalent.
Intake gasket Fel-Pro 1212 or equivalent.
Use thread sealer if head bolt holes in block inter the water jacket. Torque in circular fashion per engine manufactures spec.
Torque rocker stud to 45 ft lbs. Use sealer on rocker studs that protrude into intake port.
When setting up adjustable guide plates, position guide plates so they land the rocker arm in the center of the valve stem. Tighten guide plate center clamp screw to 20 in pounds.
Exhaust ports are raised .300". Top alternator bolt hole above the number 1 and 3 exhaust port are raised to clear the higher exhaust port. Your alternator bracket will need to be modified to use this hole.
Spark plug recommendations: Race 3/4 reach 14mm thread with gasket
NGK R5671-7 4091   hottest
NGK R5671-8 4554
NGK R5671-9 5238
NGK R5671-10 5820 coldest
Street
NGK FR4        NGK FR5
Torque heads to 70 lbs or manufacture recommendation. Use hardened washer under head bolt/stud. Use ARP thread lube on threads and under washer/bolt head.
Re-torque after several heat cycles.  Break one bolt loose at a time and re-torque to torque spec. ​Rocker studs torque to 45lbs. Use thread sealer on intake studs that enter top of intake port.
Always check piston to head clearance as well as piston to valve clearance. If you run a large dome piston it may be necessary to index the spark plug gap to be pointing down to avoid hitting the piston dome. If ground strap is too close use copper index spacer washers to obtain proper clearance.
If using high lift roller cam springs. Use exhaust rocker stud that the base stud will reach all the way into the bottom hole such as: ARP 235-7203 or ARP 235-7206
Cylinder head flow:

Valve lift  .1      .2      .3     .4     .5      .6     .7
intake      75     153  122   271  315  341  345
Exhaust  68     133  161   213   240 258 263
Test conducted at 28" of water on Superflow 300 Bore Size: 4.500" intake 3/4" radius plate . No pipe