Would have to deal with the trans. Manual valve body would be one option, but, you would still be missing 4th gear, and TCC. 95 or older trans would get you the first three, but, would still need to address 4th, and TCC.
Gauges would be another issue. You could leave the PCM hooked up, for the most part... so it would supply info for the gauges, or, you could convert to different gauges.. PCM would be setting numerous codes... for all the things it wanted to do, but didn't make any difference, also for sensor that weren't there any more.
Just out of idle curiosity, why do you want to take several steps backward in technology?