I doubt that your transmission needs anything more than disassembly and inspection.
However, if behind V-8 power, often the main drive gear bearings need to be replaced.... in particular the AFT most bearing.
If memory serves me, these are an industry standard 30207 and a 31307 tapered roller bearing.
(no need to buy the same exact bearing from v/p)
Your A transmission uses a crush sleeve or pre-tension sleeve to control the rolling torque value.
Your A transmission bearing box is gasket style shim controlled for the gear contact/back-lash.
The double row angular contact bearings (the support bearing for each "driven" gear) seldom go bad.
These are rather unique to V/P, as I've not been able to find an industry std bearing replacement.
Watch the shims that are between the bearing and the gear case.... they must go back in as they were.....unless you also change these bearings out.
As for the lower DP unit, you can build one of my prop shaft bearing carrier puller tools, pull the carrier out, and take a look at the insides.
Look for gear tooth condition and bearing races for signs of wear.
It is more likely that the lower gear unit may require an over-haul rather than the transmission.