If you are chasing a bolt in replacement, You need to find an original one. The 1k has a very low profile engine bay, so most radiators are too tall.

Pretty much everything will require you to modify the radiator somehow.

I have a couple of 1k tanks and straps if you get desperate

So far you have a choice of early corrolas, gemni, 1200

I have heard of people using hyuandi excel ones...