My father did more than 100,000km (62,000mi) on his early 1980s Enfield Bullet 350 - Cast Iron. He had no major problems with the bike, which is very surprising. Just did the usual oil change, points check, spark plug, carb, de-coke, chain etc
In my opinion, the UCE should manage at least that amount, considering the improvements and the more reliable nature of this motor. But that does not mean that we don't have to take care of the UCE. If we keep following the service requirements, keep the sprag clutch on the safe side, and ride at comfortable speeds, the UCE should give you many many happy miles.