I once looked into having the R452 26 tooth input gear made by my Japanese gear cutter with the 10 spline Jeep input shaft but after having trouble find the transmissions thur my importer, I dropped the idea.
If I could find a good source of used cores, this still could be done.
The retainer plate that I make is for the center mainshaft bearing.
From the factory, all R series transmissions; 150, 151, 154, 452 ect., all use a stamped steel plate to retain the bearing. This plate is prone to wear that is one of the causes for the trans popping out of gear.
My plate is CNC machined from tool steel and comes complete with much stronger bolts.
Marlin