triple tree crown

hello friends, newb here. picked up a 76 and the PO said the front end had been swapped. did some research and looks like a sr500 front end. which is great and all but i am stumped by the top triple on this thing. it has no pinch bolts? just the top fork bolts. that can't be normal right? can't...

A few years ago, I acquired this upper fork crown.....it was supposed to be from a Ducati.....now I am attempting a fork swap and have NO lower to mate with this.....the tube holes are 53... but the spacing between the tunes is NOT 152mm like a normal Ducati....it's closer to 5-1/2"....does...