I got to say it.. Its the big block that is slowing your A-body down. Everyone likes the idea of a big block in an A-body, and that It is going to be soo fast.. Reality check here.. I know this is not helping your need, and this could be covered under a whole different thread, but like I said had to say it.. A Stock 340/ good 360 with stock cam and manifolds run better than that all day long at the track.
More than likely get your timing right and Carb right, and proper traction you will pick up 3-5/10ths. Like the guys are saying. your not going to see low 12's, without a lot of changes in gear, traction, and more H.P
