My 340

F21 said
B1 cylinder heads
Hand ported have not put them on the flow bench yet I believe about 260 ish hopefully more

260 ish is the stock rating.

F21 said
So now let’s do the guessing game. What do you guys think it’ll run in the quarter-mile And estimated horsepower

It all depends on the heads, if your only 260 ish cfm, I'd guess around 475+ hp.