18r should be a fairly easy swap, anything not from the r series is probably going to be a lot more work.
If your total budget is 2k youre not going to get far. I assume you mean to buy your engine, if that is the case, I reccomend a beams engine as there are a few rwd options that make sense for that engine. Plenty of NA HP. If you already have a w55-7 then you will find it fairly achievable.
Plenty to read about Beams into ae86 here, but a lot of it transfers over.