Drives:
Concerning your vintage power tools, there is a good market for them. However, the market is limited to collectors. The price, condition, & owners manuals/boxes are a plus. However (IMO), they are undervalued, like vises.
Here's some pros & cons:
Pros; They're cool...to the point that your friends will envy you, bulletproof...will last forever, and easy to repair... I've only replaced brushes & cords, and lubricated them.
Cons; They're heavy as hell, vibration is a problem, and they aren't as safe as the newer tools...electrically & mechanically.
As far as the electrical goes, if the cord/plug isn't grounded, you can replace it with a grounded cord assembly and attach the ground wire inside the metal housing. That will eliminate that occasional shock you may get from those tools under the right conditions.
I have all of my Dad's tools from the 50s - 70s, which I'll never get rid of. The cords have been replaced as needed. However, I also have a collection of cheap power tools acquired from yard sales over the past several years that are lighter to use, and won't bum me out if they burn up or get stolen.
Happy Trails!