That Firebird is EZ prey to a hi-po engine swap.Check yer local wrecking yards for late model or low mileage cars. You may get lucky & find a LT 1 with transmission.Check e-bay & you'll see that there are engine, trans, computer & ex. sensors for less than $2000. =^ )
If you're doing yourself this should be pretty easy to find. If you go to an auto parts store or even on line you can find a multitude of these G.M. engines. Then all you have to do is pick and choose what you want or need.