Waterless Coolant

Until you get your system sorted out, I highly recommend straight water with a water-pump lube,and a 7-blade direct drive fan,installed as close to the rad as you dare. Remember; it may want to suck the rad in at high rpm, so easy does it.
Afterwards you can experiment with anti-freeze,a thermostatic clutch, and after that, pressure reduction.
IMO, sacrificing cooling system capacity for oem appearance is ummmmmmmmmmmmmmmmm, a bad idea. How much is a motor-job worth?