I am about to do the swap this weekend and switch out the 305 for 350 out of 91' truck. I have a 89' formula and wonder if there is going to be a very noticable difference in performance. Can anybody tell me what the horsepower difference between the two engines and the amount of horsepower each engine produces.

After my L05 Swap (350 TBI out of a similar vehicle as yours mine was a 91 1500). I noticed a slight noticeable acceleration difference from the swap. Of course thats comparing stock L03 to L05. After a few bolt ons like intake, headers, exhaust, some tbi mods the noticeable was night and day.

Was it worth it? Little bit.

As for performance numbers, Not really sure about that.

I already have headers and a three inch exhaust. Plan in doing some of the tbi mods and performance distributor and coil. On the exhaust I plan on taking out the catalytic converter. With these simple mods done this should add some horsepower to this swap.

Does anybody else out there have any input? I would like to know any other opinions.