There is a lot to this , seriously your Best cooling by far is a 5 or 7 blade clutch fan with a shroud , no electric fan comes close .
ELectric fans never move as much air as a clutch fan but also do not compensate on the highway & can block natural air flow .
second Alum rads must be isolated in rubber mounts , they will crack or pull apart mounted solid to the body like brass rads , look at any new car all rads are rubber mounted / isolated from the body .
Get a top quality rad welded not epoxied double core with wide cooling passages or triple layer cores .
Yup, cause they are effective. Back in my short track oval car racing days, tried a variety of fan combinations. Most effective was a large, fixed blade fan with a clutch. Anything else would eventually creep up the temp and boil over.