Congrats Chaded
Ive got a semi custom 52cal based on a LRH barrel/action. I was going to sell it but it shoots so good with the 325gr FTX and around 130gr of BH209. Recoil is a bit brisk in mine but im using an Elite composite stock atm. Hornady has finally started selling the .458 250gr Monoflex if you are looking for a lighter weight bullet. Pricing isnt bad either (sub $40/50) and its a tipped monolithic bullet.
The 52x458 sabots are really tough and IMO the way to go in the 52cal. They will handle any powder charges the gun can handle.
The 52x475 sabots are cool but bullet selection isn't as good. The .475 325gr XTP HP is about the best ive tried if you want to try the .475s. They are kinda pricey though and don't fly nearly as flat as the FTX. Speer offers a .475 275gr DCHP but its really short and sits VERY deep in the sabot. Speer also offer fairly affordable .475 325gr if you can find them in stock but ive never tried them.