Just looking for a point in the right direction. What would be the best bang for my buck when looking for an engine to replace my 5.0 in my 91 firebird? Also want an engine that is on the easier side to put in

 

Any Gen 1 small block is a direct swap. What complicates things is what kind of induction you have. Is your 91 a throttle body injected or Tuned Port motor? In either case, some changes will be necessary to accommodate the new motor. Both are well known and a quick search should give you everything you need. In both cases, a mild 350 will be an easy swap. If you decide on a radical 383 or 400, obviously more extensive fueling/induction changes will be needed.

 

Just thinking a mild 350. Something a little better than the 170 horse power plant that's in it now. It's a tbi 5.0. So any first generation small block will bolt up to my induction system without too much trouble?

 

As usual, the devil is in the details.

Your induction will bolt up to any '87-up cast iron head SBC. It's the heads that matter, not the block, as far as the induction is concerned. The difference is the angle of the middle two intake mount bolts on each side - '86-earlier (and aluminum heads, for what that's worth) were all at 90 degrees. '87-up, those 4 bolts are at 72 degrees. Doesn't make a difference as far at the ports or anything else matching up, just the mount bolts.

'86-up had one-piece rear main seal.

'87-up passenger cars had roller lifters (which affected lifters, cam, cam timing gear, and cam retention). '87-up truck blocks were the same castings as passenger cars, but some didn't have the roller lifter provisions machined in them.

Since you have TBI, the 305 computer won't be happy with a 350. But, the TBI forum can lead you where you need to go with that.