This is a "MOTA PERFORMANCE" two groove, 6 inch diameter for a 289/302. The "front" groove ends up pretty much in line with the y-block 7 inch OD pulley. Fits on a 5/8 pump shaft and has the same bolt pattern as the Y pump flange. If a different alignment is needed - you could use a spacer under the pulley to move it out one space - so long as the spacer includes a nub to hang the fan on. 
I found the best price for them through an Amazon search.