Make sure your friend had the radiator shop ensure the original FIM radiator has had its internal baffle modified per the TSBs. I don't know what the SN of the car is but early cars had a vertical baffle splitting the tank in half which was found not to work so they modified the tank baffle for a horizontal plate. Water comes in, goes across, and then back the other way and out.
Regarding fans, I have two pusher fans mounted on the front of an original radiator. There is not enough room to mount them from behind. I used the plastic ties that came with the fan kit. Carefully push them through the core. Been there for 30 years with no leaks.