If you really loved the Rotel and it checked off on all the boxes you needed, then maybe a rebuild would be in order. It sounds like you are looking for an upgrade so I am not sure that is the case. Suggest you move on.
As far as upgrading parts with premium caps, etc. not sure I would do that to 20 year old circuit boards/associated aged components. Could be a big investment with limited duration return. If it were a newer amp, component upgrades would make more sense to me.

