hello john, so your in the middle of building a 3\4 ton chevy and running a 350 sbc. well you ststed that you want to use a 9" ford rear end and you think that it's too heavy? is that the rear end that you think is too heavy or the whole truck? if it's the rear then i don't think that you will have to worry to much, the 350 will be ok imo, and all you have to do is select the right gearing to push the truck the way that you want to.maybe around 3:55 or 3:90 should do it but double check with some of the other guy's in the club to make sure and good luck in the build dave