Duster 383 cooling issue

Just measured mine and from the face of the pulley where clutch mounts to the top seam of radiator is 2 1/2 inches. Figure about another 1/8 inch to the core and i have about 1/2 inch clearance. Tight yes but works with no shroud. We used to run a 3/8 mile dirt oval Camaro @ Fernley near Reno with 100 plus temps. Tried the electric fan no good went with a cheepo solid and ran it like that for years. With a spacer you could get some more clearance to your liking, remember those flex fans DO FLEX and quite a bit. My $$ is on the shortyclutch and a good 18 or 19 inch 7 blade.