depends on where the motor is sitting.

In mine i can fit a 3 inch thick cooler, my camry 2 core radiator twin davies craig 12 inch thermos and still have a bit of room to spare before the front pulley

Pretty sure s13 radiators are actually too big to fit properly in the front of a 1200 anyway. people use them but im sure there are better fitting radiators out there

Also im not really a fan of the ebay $2-300 alloy radiators. Probably better off spending an extra hundred and getting a cutsom made copper one from a good radiator place. Then you can have it made to whatever size you want and know that its of better quality