So it's confirmed I'm an idiot! The MT4 is in fact a 19 inch frame... I can't even remember how this came to be.. with that out the way...
Let the rebuild commence, some photos from today...
The m900 is being swapped out for m735, some cleaning and lubing still to be done... but mostly...
I think its in the for sale section.
https://www.retrobike.co.uk/threads/reduced-1996-marin-rocky-ridge-19-inch-pace-rc30-forks-dx-group-deore-brakes-mavic-mix-%C2%A3250.498733/