I believe in an FC you can fit a 27.5x19" radiator.... but a 27.5x15.5 or similar should be more than enough. I have the smaller one in my FD and it cooled an LS7 track car with no issues (fully ducted up front).I like Howe which are good bang for the buck. There are plenty of cheaper ones....https://www.summitracing.com/parts/hre-342aaOn my cars I run a Ford Taurus 16" fan which pulls a ton of CFM. The Volvo V70 and similar fans also work great. https://www.motortrend.com/how-to/ccrp-1111-electric-radiator-fans/