Would it be better to pick-up a second hand/recond box and fit that? Keep the old one, repair "at leisure" and keep for future use/sale?
Other option is could you remove the gearbox at home and "send" off and save some serious labour hours. Good option 
A Morgan Identified Fastidious Owner...
2011 4/4 Bespoke, 1981 Delorean, Auburn Boat Tail
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