I won't be here during the week but you and Ricardo and any other helpers you line up are welcome to use the shop.
I'm willing to bet most of your compression loss is from poorly seating valves that the new valve job will fix. On the other hand it's pretty easy to drop the oil pan at that point and replace the rings & rod bearings. Eespecially if you plan to replace the front seal requiring you to also remove the timing cover.
As far as the rear main seal, keep in mind you will also have to drop the tranny/TC in order to replace it. So you might as well replace the clutch & pressure plate at the same time too.
Randy Rosetta KDØKWX TLCA #19351 69 FJ40 "Meanie" & 1970 Boss 302 Mustang