That’s a big reason on downconverting to the LA Flat Tappet Cam & Lifters. Replacement Magnum Roller Lifters are priced like they’re made out of Gold & Platinum with Unicorn Tears for assembly lube. And the lifters/Cam in this 5.2 are wrecked.
Sadly, this isn’t a one time occurrence for me. The Mid-80’s Roller Cam LA 318 that I picked up to build a Stroker for my Dodge D50 also has flat lobes and trashed lifters.
Don’t remember the chamber size on the J’s off hand, but that’s easy to measure. I had them shaved about 15 years ago and ran them on a 318 in a Dodge D50 and then the engine gathered dust in the shop and eventually became parts for other engines.