Sounds like you have an ea82 sitting around and want to replace the engine in your brat with it because you can't find a decent ea81.
I did this 3 years ago ( SPFI ea82 ) in an auto brat as a temporary fix until I could afford to change to ej22. The only real problem with install was (for the automatic) I had to move the proportioning valve and for the 4 or 5 speed you will have to move the hill holder also. Everything else was normal engine swap stuff (hoses, fuel, etc.).
Other than the wiring I had the swap done in one day but I had several parts cars to pull pieces from. Thanks to GD's write up I did the wiring the next day and had it running that weekend. If you do it reseal the motor before it goes in especially valve covers as it is to tight to remove them after it goes in.
That said I currently have an ej22 on the engine stand being resealed to put in it.