Selection of Torque Converter and Rear Gears for Hot 340

150 in an A-body must be freaky fast.
My barracuda used to cruise real nice at 100 for hours,120 for shorter hops on the interstate following faster cars. But when I crank it up to give chase, I try 140 briefly, then lose my nerve. 140 is an awful lot faster than 120. And ohlordy the wind-noise!
I can't imagine 150 in an A-body.
OP
If you are higher than 4000 ft, you got some thinking to do. That difference in elevation, on a true10.5 engine, is over 20psi, compared to sealevel, and basically makes your 340 feel like a smogger-318@ sealevel, until the Rs get up..
So, if an original 318 car ,then just go straight to the compression test, then check your local elevation; these two go hand in hand.