manual to automatic swap

My daily driver is a beat up 86.5 Supra. I'd like to swap out the 5 speed into my wife's 90 Cressida; which is fairly simple. My question is can I put the Cressida automatic into the Supra and continue to use it as my everyday beater. I don't have the time or interest in changing out the whole wiring harness. Is there a simpler way to have an operational automatic; or should I just part out the Supra and make the Camry my daily driver (ugh).