What I have done seems to work great .
I bought a composite fan shroud that has to be cut out and enlarged the mechanical fan from 15 inches to 18 inches. I have the stock radiator and a new 302 GMC straight 6 . During the break in of the new motor, it never got hot and the worked so well that when idling, the condenser electric fan ( pusher) spins fast from the mechanical fan draw.
It was easy to cut the shroud to fit and I had studs welded on the radiator to accept the shroud and keep it in place.
Hope this helps.
