This may not help the OP, but the SUM-6900 cam and lifters is what I ended up using in my 74 318. Bone-stock low-compression bottom end with the cam, duals, and an 1406 Edelbrock on a Performer intake. I currently still have 2.76 gears and a stock convertor. I noticed no loss of low-end and the mid-range is much-improved. It still pulls 19" vacuum and sounds almost stock to me. I know there are better cam choices but, for the money, I am very happy. Crossing my fingers, it hasn't went flat yet after about 5000 miles. I think it will really run well when I get around to installing the 3.55-geared rearend.
