HW35's are easy, thorough clean, seal the breech, reduce TP dia to 2.6 to 2.8mm if a 4mm one, drop a new seal on and they shoot well. All the vixen had that was remotely special was a sealed breech, everything else done was cosmetic imo.

To give an actual example, I sealed up a 35 Lux a few yrs back now, 9fpe at best, sealed breech with same spring was doing 13+ (gun is .177) I shortened the spring, installed new guides, vortek piston and breech seals and cleaned/relubed the trigger...took 1 hr to rebuild and test once the breech had been sealed over night. It was one of the nicest shooting stock 35's I have done...sweet as you like.

No fancy chromed piston and spring...not needed

To see the ultimate 35 have a look at T20's build thread....now thats a HW35 and some.