What's the difference between these wheels?

[Mart]

The rears are stock 35 and you can see the 5 nubs just inboard of each stud. The fronts look like 40s repro drums, as the surface is flat. From the angle of the pic it is hard to say for sure from here.

On my roadster I run 40s steels on the drums like your original rears and cut/filed the nubs off to give a flat surface.

Has your car been converted to hydraulics?

The 40s wheels should fit the front but something needs to happen at the rear.

The centres of your front wires may have been bent a little out of shape from being fitted to the flat drum.

Mart.