Thanks all, for your kind replies and helpful suggestions!

Quite impressive what already has been done with the oldies. I´ll keep my eyes open for a suitable cheap enclosement, in case my last Bondi´s PAV dies.

Good to know what could be done. I might also plug in a CRT from my MacII for some time, if the need should occur.

The old PC boxes are of such an outstanding uglyness...

There are some affordable working G4s on ebay that might outperform anything I could possibly make out of my remaining parts - for even less money.

I´m not quite ready to decide, time will tell.