...and depending on the final tire diameter, you may wanna go deeper yet.
i've put 4.56's in a 72 chevy with 30" tall tires.
here's a ballpark way to get close on the gears,
after you get it running,drop the trans down in 3rd (1 to 1 ratio,not od) and see what the tach sez.you wanna shoot for around 3000 rpm at 60 mph.
you MAY wanna go the next step down in gears with that 4.3 as they really don't have the power of a v8(don't get me wrong, i LIKE 4.3's)
there's programs on the net for this but i can't find the link.
try a search for bowling automotive math...
turning too slow down the highway is just as bad as too fast, it'll eat just as much fuel...
