Hello Andy welcome to TalkMorganwhich I wish it was around when I rebuilt my Morgans.
I think my advice would be start with the chassis. It needs to pass a MOT and be safe. Areas around the rear spring hanger and where the bulkhead bolts to the chassis down in the footwell are good indicators. If the chassis is good or repairable then the wood subframe is next. Pull the leather/leathercloth and horsehair off covering the chassis sides under the doors and you will know what needs replacing. The wood above the rear number plate and the ash running along the top of the chassis are also favourite places for rot but just have a good dig around. It is surprising how much of the wood frame will be in good condition.
I have taken apart four 4/4's and only one needed a full chassis up rebuild. The best ones were like yours not used for a long time and abandoned in a garage and a barn.
I found them all very rewarding and were eventually sold at a good price. Morgan parts, however, were very cheap at the time. How about inner wings at £16 the pair!
