hey Eric ..thanks for the info about hole spacing etc..At least with the P83 mounting position is less critical than the P87 where if you get it wrong it becomes very wrong... The more modern P87's holes are separated further..
It turns out my snare is actually a 5.4" (5.5") Jazz Festival but I've gone through the exercise making sure I know which one I have ...hopefully that's the end of that saga!!
On the bearing edges, yes the originals are very rounded, and I've noticed too the snare beds are wide and quite shallow ..some like it this way ... If you are going to re-hone your bearing edges either use a router table with a 45 deg chamfer blade from the inside and go little by little...First use a 10mm thick sheet of 600 x 600mm glass with a big sheet of say 150 grit snandpaper to achieve a flat bearing surface on both batter and reso sides (this won't be touched upon routering as it's the apex of the outside round and the inside 45 batter....
One of the things i have noticed is the shells need to be checked carefully for any delaminations that may have occured these should be fixed from the outset ..go to Vintage Ludwig Snares and Drums facebook site for inspiration!!
I'm going to go for Remo heads when finished and 20 strand Puresound conventionally strung snare wires
As for how round you make the bearing edges this is up to the individual but the internal poplar or maple (white wood) ply should be in the middle of the bearing edge apex, and the 45 deg batter should meet the outside slightly curved batter at a distinct point that can be rounded using say 220 grit sandpaper on a flat cork block. Then put back on the glass sheet for final honing