451 overheating, even when moving

If you rev that engine and watch the fan blades, they will actually flex forward towards the rad, reducing the distance more with higher rpm .
The motor won't move much, as the rear mount is captured by the rear crossmember .
My son's clutch is about 1/4 inch from the rad, he's a very spirited driver, no interference in a decade.
The only interference I have experienced was a missed shift sucked the fan blades forward into the top of the bottom tank, split it wide open .