Of course you can do it.
None of the approaches is rocket science. The Brassworks setup looks pretty cool, and must come with wiring so that all you have to do is get a high power feed up to the fans, and the sensors and relays do the control work.
Option #2 & #1 probably have a lot more wiring challenges.
I was surprised to hear a radiator repair / recore would be that expensive, but I haven't priced radiator work in a while.
Good luck. You won't have any (major) problems with any of your choices.