Just a little FYI ! years ago I broke the 340 in my 68 Dart race car , I bought an original 318 out of a 68 Charger we did a quick valve job , put in a stock type 340 cam and an old LD4B intake, Holley 750 , 1 5/8 headers and the car ran 13.90s with a 3.91 gear. I put on set of 360 heads and the car ran 13.20s . I took out the 10 inch converter and put in an 8 inch Turbo Action converter and the car ran 12.60s . ( I run a 904 )