340/drivetrain build advice

For mid 12's and no head work (AKA Porting)

Use a Hyd. Cam in the 244* range or advertised range of 292*. Use the valve springs recommended by the cam grinder. A RPM intake with a 750 carb (maker, your choice) , header w/-2-1/2 exhaust, stall converter to match (ask a Pro's advice like Frank Lupo or other) and a Trans-Go stage 2 shift kit. I'd use 4.10 gears with a 26 inch - 27 inch max tire. 3.91'smpossible with the shorter tire.

Upgrade your ignition. A MSD or equal with the stock recurved distributor will do just fine. Somewhere around 35*'s at 200-2400 max without the vacuum advance vacuum hose hooked up will do well. Rehook up the hose after setting. There is some play in that setting. The track will tell you if more or less is needed.

This should put you in the mid 12's firmly. Just remember everything is in the tune and settings.
In general, this combo should be good for about an easy 380hp. It is very similar to the MoPar create engine, a 360 @ 10-1 with the purple Hyd. 292/.509 cam that has dyno'd north of 400 with super comp headers (large tube) a d been in these pages in other fellas A body cars running a min. of mid 12's.

Others with more race rides have seen low 12'a and high 11's with that create engine.
In your full dressed A body, mid 12's are a state of tune and well applied torque. AKA, traction!
Enjoy, have fun! Rob