Was in CZ a month ago and was able to get a day to go and see Jiri Starec the CZ magician (hospitality plus). He builds CZ twin ports "from scratch" for 10,000 euros or thereabouts.
Had a look at his workshop (mini factory) and it's a work of art in itself, even a foundry and all the casting moulds for cases and cylinders and hubs and everything, even the ability to make the frame "as it was" and you can have any level of improvement (update) you want, he said electronic ignition is the most popular followed by mag' parts. When I was there he was making "factory" racer mag' tripples for a UK racer.
Still, he does use NOS parts where available because it's simply lower cost, for example for gearbox shafts.
His skills come from being naturally talented, trained as a rider with the Czech Army motorcycle team, CZ factory as a first class machinist and worked at the construction of factory racers.
It was very impressive but I suppose the point is that at 10k euros it's something that seems to sell in Europe only -- perhaps a bit more money over there?
But, if you really liked you CZ's and were not fussy about "provenance" and wanted a competitive bike it would be an easy way to go racing.