I have a 91 GMC sierra pickup with a 305 (tbi) that the pistons recently rusted up on. Instead of rebuilding i have opted to go with a 350. I have a reputable remanufactured engine shop that offers a performance 350 with 350 horsepower. My orginal 305 got 16.3 mph. My questions are:

1. What kind of fuel milage would i be able to expect with the performance 350?

2. Would my th700-r4 transmission be able to handle it?

I also would need a chip, has anybody had experience with tbi chips ?

Thanks in advance for your advice.