I have early 3.5" boge non hub centric front struts. Can I just replace the hub with a later hub centric hub or do I have to replace the whole strut?

I can’t guarantee the caliper/rotor spacing but both hubs are interchangeable on the strut and use the same bearings.

Yes it should fit. The height difference affect the distance to the wheel surface not the rotor mounting surface. I was looking at a pair of non hub centric 911 hubs and it loks like an adapter ring could be make to convert them to hub centric.

@steve