I would hesitate to go any higher than a 358 gear which is only 3%. I feel you could pull that fine unless you have mountains to do on a regular basis. a 346 would be pushing it in my opinion but might work if you have pretty much all flat driving. Anything higher and you would not be able to keep it going on level ground in fourth gear, IMHO.

307 and 288 will simply not work, IMHO.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.