Restored TEMP looks OK. CHECKDB is fine, and I managed to make a LOG backup from it (although presumably nothing to actually back up, as I assume having restored it the LOG would be checkpointed etc. at that point and "empty"?)
So I'm inclined to just restore over the top of the original - although I would like to stop SQL Service and take a low-level file copy first, just in case I need to examine it further - e.g. in case it helps to figure out what caused the problem