Mech fan suggestions…..

That motor will work with a fan clutch.
Water pump flange is same as stock 383 car.

Your clearance problem is from the radiator sitting too far back, aluminum pulley thickness (not much).

If you are running stock Trans mount, the motor probably isn’t shifted too far forward.

I definitely no question do not have room for a clutch fan. The radiator sit right up against the cross support and cannot be moved forward..... not without cutting or modifying the cross support. The one pic where there is no fan is with my older March pulley set up, but the pic next to it shows where I moved back to the stock OEM bracket system and V-belts to create more room - cannot get any thinner with the pullies.

I'm running one of Denny's HDK front suspensions which actually locates the motor back about 1" from stock, so there again I think I'm getting everything I can get.