85 firebird 2.8 swap to 3.4?

Ihave a 85 Firebird with a 2.8. I wanna swap to a 3.4. What year of enigines and off what vehicle can I use to do the swap? Thanks Pat

Pat, the 3.4 must be a RWD version, as the blocks are different. Also, the DOHC version is a nightmare to try to adapt. Stick with the OHV/iron head version. They're in mid-90s F-bodies. That swap will give you the least headaches. All the manifolding will fit. You may need some sort of upgrade to your computer, to get all the mixture and timing details right. A local electronics guy can set you straight on that.
Melling offers a real nice "torque cam" for that engine. We use them in the 3.1 Fieros, and love the power curve. It will work fine with stock valve train pieces, but upgrading to roller rockers and stiffer springs (small block performance springs fit) will enhance it even more. The part number (Melling) is: MTC-5.
The heads can be another source of power increase. They respond well to larger valves and mild porting, without sacrificing drivability.

This kind of engine swap is best for Fieros where there is not much of an engine selection. Adapting a 3.4 and getting the EFI up and working is a lot of expense, trouble and work for only a modest boost in power.
For the time and expense, swap in a small block Chevy engine and trans, or sell yours and buy a V8 firebird. You will have far more performance possibilities.