The AFM is a direct swap for 82-83 Supra.
IIRC up to '86 (or whatever that model was) wil lwork, but may require re-pinning the connector so it lines up. there's quite a bit of discussion from here and the old Off-Road.com site.

W/ 30" tires, you'd probably want 4.56 gears. 4.88 would be even nice but actually overgeared, resulting in higher RPMs. IMO not necessarily bad, but louder.
With the open exhaust and (if you do it) intake, the real powerband is from ~3200-4000. These motors can run all day at the high RPMs, and love it - it's just louder.
Do the math on the diference - going from 4.10 to 4.56 is about 10%... so instead of 3000 RPM it'll be more like 3300.