I've been pulling apart my 350 the last couple days, it was supposed to be a '83 truck motor. I ran the casting numbers on the heads (3986336) through mortec, which said they were '71 350 heads with a 76 cc chamber. I measured the valves, they were 1.94's. I pulled the flywheel off, which had painted on it " '74 chev" I took the oil pan off, and found it was 4 bolt mains. Yet when I ran the block number on mortec, it said it was 80-85 when I first bought the car. Is this normal for an 80's block, or is mortec wrong?
Anyways, the motor is going to get the basic bolt ons ( headers, intake, roller rockers, etc..) but I'm wondering more about my heads and compression. The motor runs fine on unleaded 87, so my compression obviously isn't all that high. I'm sure I'd benefit from more compression, but would it be worth the cash? I'm not looking for a ton of power, but somewhere in the 250-300 horse range would work. The motor has to go back together in a few days ( I'm takin up my dad's garage ) so any advice would be appreciated.

336 heads are plenty enough to get 300+ hp from. If I were in your shoes I'd zero deck the block and have .025-.030 milled off the heads. That would put you up around 9.5 compresion. If you don't have a stall I'd use about a 210-215 @ .050 cam. If you do have a stall or a manual tranny, use about a 220 @ .050 cam. With both cams choose one with 6-8 degrees more exhaust duration. With a 224/230 @ .050 cam, 9.5 compression, and unported heads, DD2000 claims right at 350 hp and almost 400 torque.

BTW, if you want a steal on some 1.5 ratio aluminum rocker arms, I've got a set I'm not using. Just email me and let me know.