Anyone here good at estimating horsepower/torque?

I've got a pontiac 400, with stock big valve, #16 heads, 9:1 compression, large tube headers, 4 barrel dual plane, 223/231@.050 .465/.488 lift.

How much power should I be making??

Its kind of hard to say, you should just go and have it dynoed.

What year block is the 400 and is bored?

425hp 450tq at the crank

Sorry for the wait. Block is a 75 and bored .040 over.

I'd love to have it dynoed, cause I really need to tune it better, but I wouldn't even know where to go or how much to spend.

I'd be ecstatic to find 425 horses. Do you mean gross or net?

Net at the crank. About 340 at the wheels. Good enough for 12's in a properly setup car weighing 3500 lbs.