I would get different size Rega spacers and get one of the recommended cartridges. Previously I had a Rega Elys on a P3 (sorry can't compare to the exact) and replaced it with the basic Denon DL103, better bass, more detail, more live. The DL103R is another step up from the basic version.
Another option to consider is the Kontrapunkt A which can be found on Agon for around $400 and from Needle Doctor for a similar price. Look at some of my recent responses in Viggen's system and my system for a very basic comparison.
Both the Ortofon and the Denon require spacers for vta. And both require a good MC phono stage. For MM you could try the really cheap DL160 high output MC. You might get surprised how good a $150 cartridge can be.
Another option to consider is the Kontrapunkt A which can be found on Agon for around $400 and from Needle Doctor for a similar price. Look at some of my recent responses in Viggen's system and my system for a very basic comparison.
Both the Ortofon and the Denon require spacers for vta. And both require a good MC phono stage. For MM you could try the really cheap DL160 high output MC. You might get surprised how good a $150 cartridge can be.