My cousin has an s13 with blown motor, that happens to be an Auto.... he offered it to me for 300 bux, half the engine ripped out, and he'll tow it to my garage

(i think he started the project with gusto, but then realized that it wasn't gonna be an overnight racecar)
is it worth doing a DET swap? will the tranny conversion be a downer to the operation?
the interior is shot, there is a kinda large rust spot on the drivers side A pillar, but other than that the chassis is clean...
just wanted some other opinions
Thanx!