John,
The only garages that we use locally for our Mog's are SGT, I've already given Taffy a write-up above, and
Millers Commercial Motors who despite the name are Mog enthusiasts and know the cars backwards. The owners post here as 'Oldtimers' and 'Cerealsurfer' and 'Young-One' are part of their family and also Morgan racers (see the hotlink above) and owners respectively.
You won't go wrong imho with either option.
Cheers
Brian
