Are the transmission brake drums made out of cast steel or cast iron? If cast steel can the lugs be built up with wire weld by using a lower heat range and alternately doing a little at a time to eliminate overheating and warpage. Also will the lug shoes from a 26-27 brake drum fit earlier drums if the shoes are shortened?
I have some old transmissions that I acquired that sat out in the weather for many years. Its amazing to see the grease still inside of them and shining shafts when you pull them down. Although there is rust on the gears I will do some major cleaning and some bead blasting and see what things look like . Do not want to discard if they are usable.
Also , how do you replace rivets in the transmission drums? Thanks

I'd avoid heating an original brake drum, although modern wire welding is a lot safer than the old stick welding or brazing. If you're willing to do all that work that you ask about, I think you'd be better off all around if you used an air file or square hand file to reduce the lugs' diameter to that of an original late '25-'27 drum and use some good lug shoes. Just be certain that the lugs are filed evenly so that the center distances stay the same. Otherwise your shoes won't line up with the disk slots in the clutch.

We thought that whittling the lug down to accept a '26-7 shoe might be a solution, too, until the work of reshaping was done. Notice that the late drum differs from the earlier design in that the lugs do not coincide with the bolt bosses for the drive plate:



In my opinion, the reworked early drum doesn't have enough material left for a secure assembly; the modification severely weakens the lug. The last thing you want is for the things to tear loose when you step hard on the brake pedal.