First thing you should do is check your bearing cups to see if they are cracked, scored, or pitted. If they are, just get a new wheel.
If they are still sound, I'm guessing you will need a 3/8" X 26tpi axle. Most solid axle wheels from the 80's and 90's use those.
Also guessing the bent part is on the drive side of the axle, this is why cassette hubs ended up taking over the market- it allowed the part of the hub that carried the load to be closer to the dropout, so axles were less likely to bend.
Take the axle and cones with you to the LBS, and carefully try to thread the cone on the replacement axle.
If you get new cones, they should match the profile of your existing cones.
Get new bearings.
Good luck!