Space around my fan shroud?

Im with you they work best wall to wall but I dont think the 1/4 inch is gonna hurt.

Agreed. I'm not so concerned about being 1/2" short side to side, 1/4" short per side when centered. I'm more concerned that I'm losing out on being 1 3/4" short on height, 7/8" top and bottom when centered. My math shows that it would still cover 90% of the core surface.