what is the best way to polish/ slightly resurface irons and housings

 

Are you asking about internal or external area of the parts?

 

internal

 

rotor housings can be cut down as a way of refreshing the sealing surface. side housings can be lapped and/or re-nitrided. both are only to a point before you'd have to consider replacing them.

neither of them get polished (if you're talking about what i think you are). the surfaces need to be porous in order to retail oil (in addition to being able to provide a surface for the rotor seals) for the engine to function properly and last for a decent amount of years/miles.

 

What i mean Is like honing your normal engine on a rebuild, is just some high grit sandpaper/ lapping good enough. People say re nitrite but there is no way hand lapping is aggressive enough to do more than hone

 

Kyle Mohan has talked about lapping irons in a few different videos on his channel. Here's one of them:
I think a few people have talked about going over the rotor housing surface using a drum sander, but I don't think that's been proven to the same degree that lapped irons has been proven.