What are these called (currently on a 78 F700 I'm looking at), and are they upgradeable to a newer style without spending an arm and a leg?

 

Dayton is the actual name and company that makes those. Also called "Western" at times.

The "upgrade" there is to tubeless via new rims that will fit on those centers.

Those are much better than having a set of widow makers on the truck.

These folks should be able to help, and there are others as well. Under $200 per copy, who knew?
https://www.southwestwheel.com/c-855...able-rims.aspx

 

Whatever you do, back off all the lug nuts but do not remove them totally. Take a small sledge hammer and give each clamp under the nut a brisk tap. They're under tension and can fly off with some serious force if the nut isn't there to restrain them.

 

those are known as California wheels. they used to be pretty common.

converting them to 10 hole buds would require new hubs, and wheels of course. hardly worth it most likely.