Any 7" non sealed beam light will fit. I suppose there may be light units that don't take H4 bulbs (standard halogen headlight (dipable twin filament) but I've not seen any. The only other issue is whether the lamp bowl has a fitting for the side light bulb. If not, you can get a twin filament (side light/indicator) setup for the standard Mini indicator unit.
I used to use some old (Lucas) light units I found on an old LandRover at the local wreckers.... with modern high powered bulbs.
Older units can be advantage as the bowls are usually metal so can take higher power (hotter) bulbs. Some modern units are plastic

Cheers, Ian