so let me get this straight. You are planning to get an mr2, either a mkI or a mkII, and you are planning to do an engine swap, just for the hell of it, and you dont know what engine you want to swap in...
well, if you get a mkII, there is no need to swap in a new engine. The 3sgte is a strong engine, and if you put a larger turbo on it, and a manual boost controller, you will get plenty of power without having to spend a whole lot of money.
I would recommend the mkI however. They are much cooler and more rare. I have a 4A-GE in both of mine. For those who dont know, that is the stock block. The blue-top 4A-GE, that which comes stock in the naturally aspirated mr2 from 84-89, puts 110hp at the flywheel. Both of my cars have the red-top 4A-GE from the corolla gt-s which is higher compression and puts out 140hp to the flywheel. If you are going 4A-GE, the cone filter intake mod costs about $10, and gives you an additional 5-6hp. The best mod you can do is cams. A local cam shop here in Vancouver, Canada cuts very very good cams for the mkI. tested before and after on a stock blue-top, these cams added 27hp at the wheels. My faster mr2 is pushing 225hp with the 4A-GE.
If you want to do a swap, I would highly recomend the black-top 20V 4A-GE. It is highly sought after, and gives really nice naturally aspirated power.
If you have the funds, and the means, I would recommend swapping a 3sgte into the mkI above all else. They call this the mk1.5. Ill attach a really nice video of a 4A-GE mkI going against a mk1.5. This swap is so cool, and for those of you that havent seen a car with this done (probably all of you) it fits beautifly in the engine bay. If I had built up my blue car, I definitely would have gone with the 3sgte. I also believe that in Canada and the US, swapping that engine in is a smog legal swap because it is out of a later gen mr2.
You could also turbo charge a 4A-GZE if you want, but I wouldnt recomend it. It requires a heck of a lot of custom fabrication. I hope that answers your question.
85 red Toyota MR2
93 infiniti G20 (sold)
86 mr2 show car
UCP's most totally hardcore crazy MR2-or-anything-else-that-runs-on-4A-G-power fan. I rilly like MR2s