What size carb for a stock 350 engine would be best for fuel economy
and performance? Edelbrock 650 cfm okay?

A 650 would be ideal for that engine.

i had a 600 cfm holley on my stock 350 and it seemed too big for my particular setup. i ended up changing out the main jets to a smaller size and also i added a different power valve and then my mileage went up from 8 to about 12 in the city. then again, mine is a C10 so its lighter and not 4x4 like yours, but your mileage would probably be at least in the double digits in the city lol