Water pumps/pulleys

[seanrolandwood]

So i ordered a new water pump from summit it mesures 5 7/8" from floor to top of flange my old water pump mesures 5 5/8"....yeah a quarter inch difference as you can imagine my balancer pulley no longer lines up. My question is did i get a short pump for a serpentine pulley system and not a V belt system..is there a difference cause i didnt notice any selections that differentiated between the two...I've done some research and found articles listing those sizes as correct for gen 1 sbc short water pumps only deepening my confusion.
Please any help would be greatly appreciated as I'm hesitant to put some kinda spacer between my balencer and pulley to try and even things out.