[ssa_is_shit]

In that area, you have several possibilities. Hopefully, it is just a loose connection/clamp on the cooling lines. I know it isn't fun to put your hands in there and feel around, but you should either see or feel a small leak at one of the engine block lines or maybe the heater core connections (in or out) at the firewall. From my experience, with an SR swap, the heater connections would be the most likely culprit. They are relatively easy to see and you can reach them to check for tightness from either above or below.