When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
To answer the first question, yes, your current tranny will bolt up to a 302. But what is it you gain by only going up 2 cubic inches? If you want a good, solid workhorse, stick with the 300. It's more than capable. If you really want to swap that 300 out, then go with a 351W. Your 4 speed will still bolt up to it and you get a good all around engine.
With 7" of lift and 35's, whether you stay with the 300, swap in a 302, or step up into 351 territory, you'll likely get the same mileage........just short of crap. Your pushing a lot of mass with those bigger tires and you need a lot more go-pedal just to keep up with smaller rigs.