will a 89 tbi 350 mainfold fit on a 78 stock 350 engine?

Yes it will. :p

wait i thought intakes changed patterns in 87? tell me if im wrong if thats the case it wont work

The center two bolts on each side of the intake go in straight down on the TBI manifold instead of on an angle like the older manifolds. The TBI intake can be modified to fit, although I have never done it personally.

If you are talking about exhaust manifolds, then yes.

Intake manifold will fit with minor grinding. The center two holes on each side need to be ground on top so they are parallel with the gasket mount surface. Then custom grind a fender washer to fit the bolt hole areas, and use four header bolts in there (because they usually have a 3/8" head).

Hopefully that makes sense.