I agree with Packlet. The Comp 255deh is what I use and it produces great torque, especially at the low end.

 

Go with a 750 cfm carb, headers, the 255 deh cam, straight up timing set and a set of zero deck pistons for a good low rpm high tq motor. 600 cfm carbs are tooo small for these motors, the. heads have relatively large ports and the long stroke benefit from the larger carbs.

 

Doing a similar engine for a friend but running a little more duration in the 265 because of the 4speed tranny. Good low end and the dual friction clutch, centerforce. 750 annular quick fuel carb. really like these carbs for 4wd and 1:1 linkage for the low end torque. MSD igniton.

 

What kind of vacuum is the engine pulling. Tring to find as much info on cams and vaccum for mud draging. You have to pull 19inches in one class and 17inches in another.

 

my 268hi energy. was about 17". what is you elevation? elevation will change your vacume signal also. run a cam little bigger in another truck and gettin about 15" vacume at 5000' elevation. will research this a little for you. kinda forgot some of this info from back in the day.

 

Mine is pulling 17-18 @ 700+/- el. above sea level.