Kirk Revolution - headset help


Retro Newbie
Just got a great, pretty original Kirk (400 vers), that I'm going to 'modernise' with new parts, inc. suspension forks.

The headset cups are the original ones - my question is, can I remove them and fit a new headset? Or, did the Kirk use some proprietary headset that can't be replaced? I didn't want to start knocking the cups out and potentially cause an issue.

I'll be fitting some older Rock Shox - NOT with threaded/quill stem.

ps: I won't be using the following parts, if anyone's interested; forks, levers/shifters, cantis, stem & bars. I'll pop a sales post up at some point.

Thanks in advance for any help