Having looked into replacing the rotten gutters once the skin was removed, I made the decision that it would be easier as Steve suggested to chop the roof at the pillars & butt weld the new roof in place.
As this was such a major structural job I decided this was best done by a professional. Matt Cotton used a mobile welder named Scott & highly recommended him, he works on alot of classics & spent 2 seasons as project manager on the TV show Car SOS.
For the last 2 days (about 12 hours) Scott has been doing the roof swap. Previously I had braced the shell across the door shuts, between the B posts & across the A posts.
We took some careful measurements of the front & rear screen apertures as well as the sill to gutter heights at the door openings. With careful marking of both the car & the donor roof cuts were made.
The roof was then tacked into place & adjustments made to ensure all the measurements previously taken were replicated. We test fitted the screens & doors to check all was OK before all the joints were fully welded.
The B & C posts are straight forward as they can be fully welded from inside & outside the car. The A post has an inner section that cannot be accessed, so once the rear section had been welded Scott opened up the front section of the A post to access the inner part so it could be fully welded to ensure all parts of the A post were joined. This was then closed back up & fully welded.
It all went very well & I am very pleased that it is all sorted, a big relief!