Not quite understanding what you're trying to accomplish.
The 142 has sprung a leak and you want to perform a stem and boot/tub bearing job. Are you also trying to use a 1966+ large capacity washer with guts to mate with the top and cabinet of the 142? This is possible and has been done. If you want the original timed bleach dispenser to function as it did from the factory, you'll have to find a 1966-1974 806 washer (please don't destroy a 906, lol). If the time bleach dispenser is not important, any large capacity 1966-June 1989 washer will get the job done (July 1989-1993 if you don't mind using the orbital transmission).
If you're working strictly with the 142, I highly recommend opening up the transmission and cleaning out that 65+ year old gear oil. Water may have also contaminated the transmission through the leaky stem seal. Also install a new lower o ring seal at minimum. I'd also replace the original fiber gear with a newer Delrin one. I always replace the clutch washers but that's just me. Fill the transmission up with 90 weight GL-1 gear oil and slap it together.