In my case that is not an issue - it came with the plumbing modernised.

The tricky bit is Imperial measurements which mean that doors, windows, blinds and curtains, in particular, have to be bespoke.

There are more unusual issues. My parents’ house had three-pin electrical sockets and also two-pin sockets (round pins). The second was a throwback to before the late 1940s, where there was no (240V) National Grid, rather a number of (incompatible) grids. We got rid of the old (200V) electrics, but I regret throwing away the sockets, which were Bakelite and would have fetched good money nowadays.