Hey, I know you said you were looking into purchasing a Univox Hi-Flier Phase 2, which (please feel free to correct me if I'm wrong) had two P90's?
Well, there are two companies I know of that make reproductions of the Hi-Fliers from that phase (They have P90's, not Humbuckers).
Here is a link to the companies and the models:
Aria DM-380 - Under $200 on eBay
Eastwood Hi-Flyer - $399
I like the bridge and tailpiece on the latter, but it's a bit more expensive. Also, if you wanted 'buckers instead
of the P90's, DiMarzio makes great P90 soapbar replacements, including the Super Distortion for a P90 slot 😁
Hope this helped in some way.