Dan,
I installed a greenhouse roof in my '74 7ECA last year. It's not a job for the faint of heart. Plunging the utility knife thru the roof is step 1, and there's no going back. Before I was finished, I had a new windshield, new interior, and new headliner. Thanks to my sweetie's hard work and skill with fabrics, the plane was down for only about a month.
However, we did not recover the fuselage. By planning the roof cuts carefully, surgically extracting and replacing some wood, and reading the PolyFiber manual about 100 times, we put it back together very neatly. My A&P was impressed, and we've loved it since.
-Alex