Quite so, Jet. Any knowledgeable owner will be pleasantly surprised if an engine reaches TBO or beyond and won't be stretching the fund so it can't meet an earlier than TBO demise of the power unit.
The Gipsy Major is quite capable of reliably reaching TBO especially in a high utilisation group. However it is more sensitive than a Lycoming to poor engine handling by its pilots, and that can lead to an earlier than necessary replacement being required.
It's vital, therefore, that Chippy group members thoroughly understand the idiosyncrasies of this venerable old engine and handle it accordingly, and that new group members are checked out not just on the aeroplane, but also on the engine. It's this lovely power unit that gives the aeroplane much of its character, which is why I've never considered a dHC1 with a non-standard engine to be a real Chippy.