What about something with 250-270 duration or slightly less, or will this be too much? How much lift? I'm settled on a dual plane intake, probably eddy performer rpm and a 750 Holley carb. I have also considered putting 4:10 gears in to help as well. Am currently running 31 inch tires. Also, there is no machining to be done here. I doubt my particular engine has even 30,000 miles. The truck right now has a warmed over 318 (eddy 600 cfm carb, performer intake and cam, ported heads, headers) that is crippled by low compression as it sits. Makes no torque in all reality, but pulls good above 3000 rpm. Would like to keep my stock converter, or go with a slightly better one. Will it be a night and day difference from the 318?