Mow much money do you have? :D
In all seriousness:
- Swap in a later 13B engine and give it a fresh rebuild.
- Install a Racing Beat header and exhaust system.
- The Racing Beat intake is also pretty good. Mind you, this is setup for the upper rev range.
- Put a good carburetor on it, like a Holley 600 (mechanical secondaries).
- Do not remove the belt driven fan!
- Put some gear in it, I don't know if the R200 gear and pinion will fit that year. Look into those. When I say put some gear, I fuckingreally mean it.
- Tune it like you hate it.
Get a really big radiator and a set of twin electric fans. You'll need it.
Do you have a lot of money and enjoy blowing seals with boost?
Buy a later 13B-REW and swap it in. Remove the crappy twin setup and put a single turbo with a smallish head unit (like a GT28 sized with ball bearings). Get the 6 speed transmission too while you are at it.
Honestly, learn how to drive it first. Rotaries are hard to drive at speed because everything you know about keeping the engine on its sweet spot is different. Rev the hell out of it.
Buy some AAA roadside support.
PS. You can do like us knuckleheads and swap in a 3T Toyota engine and tranny and feed it nitrous. It was a fun car while it lasted. D: