I don't remember the radiator, I bought it at a swap meet. It was a 4 core Griffin and I think a single 18" fan.
https://www.summitracing.com/parts/s...2049/overview/
What is your temperature before you go on track? If you are out there for 30-60 seconds, it should not hit 230, these motors tend not to run that hot in my experiences. I never have seen mine get over 215 and I have flogged mine savagely for 4-5 minutes hill killing.
What is your A/F ratio at those rpms? Are you using underdrive crank pulley? What is your thermostat?
I don't suggest rear mounted, it is a lot of work. Mine was done due to space restrictions.