What problems will i run into while swapping my 305 TBI to early model 350 and I wanna keep teh stock distributer, intake and TBI for now?

You are going to need an 350 knock sensor and ESC module. You also want to make sure that the cam is FI friendly and has at least a 112 LSA or higher. Last but not least you will need a new PROM.

Well , i just swapped out my blown 1988 305 with an earlier model rebuilt 305, and here are some of the problems i've run into. first, the engine i'm putting in is a pre-'86 motor ... it has a two piece rear main seal, whereas engine's after '86 had a one- piece seal, i have a 700R4 automatic tranny, i had to get a new flexplate and new flexplate bolts that were about 3/8 of an inch shorter than the one's on the original engine.... for a standard tranny i think you need to change the flywheel ... not sure though.

Next, the engine i got had a manifold for a carb. and i don't have a carb ... so i decided to keep my intake and TBI setup from the old engine. the problem with this was on the older heads ... the 2 center bolts on each side of my manifold don't match.. on my manifold the bolts go straight down .. but the holes on the older heads are at a 90 degree angle, so the manifold (not the heads!)
had to be drilled out for the angle ... which causes another problem ... if you do it poorly and dont seal up the space around the bolt hole ... then you're gonna have vacuum leak city ....

And finally, the passenger side of the exhaust manifold doesnt match up ... the head is just about an inch shorter and the very rear bolt of my exhaust manifold comes out Behind the head ... so i would suggest either you get a new set of heads that will bolt up to your '88 intake ... or swap your 305 heads ... which i'm not sure would work ... someone else on here would know better on that than me ... but those are the main problems i've had ...

i ended up drilling out the manifold and sealing the back of my exhaust manifold ..... until i can get some new heads that is

hope this helps a little.