Trying to see what radiator cap to use, I have a 1994 celica gt with the gt radiator but it is st205 swapped?
The cap on radiator is 1.1 but pushing fluid into over flow bottle already changed water pump and did compression test any advice is helpful.

Sry forgot to say we had a stock gt radiator cap on it and it caused a small pin hole in radiator, that's why radiator was replaced and a supra cap put on it

I'm bit confused what is the issue you have... anyway. I try to write down my experience and it might help you find what you need.

I have ST205 with stock radiator and stock radiator cap. Since I wanted "high pressure one" made by TRD I bought one called "N type" that is compatible with all T20 OEM radiators (ST, GT, GT-four). After while I decided to upgrade the radiator to aluminum Koyo one. Suddenly found that TRD cap (and of course ST205 OEM radiator cap also) do not fit at all... Luckily around were some old OEM caps available from other Toyotas. I found from old Supra one fits perfect. Lately I bought again "high pressure one" made by TRD but this time one called "S type"... fits to that Koyo absolutely perfect. More about N/S types here http://www.trdparts.jp/english/parts_radi-cap.html

The issue is it keeps spitting out radiator fluid out the overflow bottle not sure the reason

Sry again it is a stock gt radiator but the car has had the st205 swap wasn't sure if I should use gt4 radiator or if I could stick with the gt one that is on it, if that would cause the overflow of fluid