No idea what it fits. On my 340 I rigged up some 1/8 shims for Chevy water pumps to get it just even with the March crank pulley I was using--how I recall was this pulley was too large and hit the March crank pulley so I got a real 340 single groove pulley but still was off so on went the Chevy water pump shims-2 of them, that I opened up the 4 bolt holes--the big hole was the right size so I made it fit
I can post more pictures with the tape measure if you think it help