I'm sure others will disagree but there is a limit to how much stroke you can package effectively in a 9.24 or 9.28 deck height. The pistons for the 4.080 stroke crank are barely over 1" compression height with a 6.125 rod. Thats 1.50 rod ratio. More stroke means a shorter rod and then you start to pull the piston out of the bore at the bottom of the stroke too much. Technically the limiting factor is the main oil passage casting above the crank. I know BB Chevy 632 and such combos have 1.47 RR and run great but they have large bores and GREAT heads. It will take Thitek's best heads, LARGE solid roller cam and adjustable rockers at minimum to feed a 4.250 stroke on one. Just my opinion.