Starting motor swap tomorrow

I found a 4.3 vortec for my mail jeep today for $75. It's complete, has 60psi oil pressure and I heard it run. I'm going to swap a TBI intake and put a TH350 behind it. Any guesses on gas mileage? I'm hoping for 20+, either way it shouldn't be too bad. Anybody have any advice for my swap? or places I can look where this has been done before? I've used the search function and haven't had any luck. Maybe I'm not looking up the right keywords. Thanks, Kip

 

Nevermind, I had the search options set wrong.....I'm kinda slow sometimes....now I'm finding lots of useful info

 

Good luck with the swap. I am in the same swap with 4.3 th350 and D18. What is your axel ratio? What size tires?

 

I have this set-up. 4.88s and 35's

 

there is a lot of changes done to the 4.3 over the years, later models had a balance shaft in the intake. I don't know if that changed the intake? TBI from my experience got better mileage. my 92 tbi 350 got 20 mpg but when they switched to the vortec 350 it got around 15.