I bought a new cz452 .22 heavy barrel varmint as my first rimmy back in 2006! It's been a great gun with no faults, no modifications, nothing. I've only cleaned the barrel once (learned from my mistake and haven't repeated), and even after 1 year laid up it was bang on target and still smooth.
Some people do the triggers, I was never that fussed by its trigger so didn't bother.
My advice, get a new or hardly used 452 and get a 1/2 decent scope (Simmons wtc scope - I have 2) a sak mod and sling and your away! I will never change mine. It's very quiet and very accurate.
Just bought a