1972 Demon 340 engine mods

Hi

A friend of mine has a 1972 Dodge Demon numbers matching car with 3 speed manual.
Car was fully restored to all original specs. Its from August 1972 which means low compression, cast crank and 245hp.

His idea is to add some more power to make it more fun to drive, but all work needs to be done so that he can go back to stock specs whenever he wants to.

We were kind of debating what to do here not to go too crazy.
The most radical idea included swapping heads, cam, intake and carb...

Since many of you guys helped me out a lot before and directed me to the right path in doing things, I am really curious on what would you do?

Thank you!