the magnum stuff doesn't bolt on. there is a boss missing for some of the bolt on stuff.

Jerry on this board makes a setup using some of the magnum parts, so they are easier to source.

But a bushing should be pretty easy for someone to make. not cheap necessarily, but cheaper than a whole new setup.

I would also check the pump itself. but if you are sure it is the bushing, I would take it all to a good local machine shop and have them fab a new bushing.
I have had that done so the race would fit in the drum hub before, so it isn't a big deal.

Worst case bug feets. see if he has the stuff to make one.
shipping both ways plus whatever he is going to charge is going to be cheaper than a whole new setup.