Hey, Jimme -
You'll get a lot more and better advice as others read your post, but I can tell you that the chassis is unique to the Pagoda. Internal M-B designation of models is based on the chassis. These cars are all categorized/identified as W113, be they 230 SL, 250SL or 280SL. [There's a later model called 280 SL as well, but it's based on another chassis and so known as the 107 among folks who are more familiar with the M-B way of doing things.] Saves a lot of confusion that otherwise can stem from all the chrome numbers and letters on the back.
What the Pagodas/113s share with many other M-B models is the hard parts; they built them out of standard sedan parts. I gather that's not much help with the situation you and your friend are in. Our sympathies, guys. Many panels, inside and out, are available. Some are OEM, some not. Some is made -- or not made, actually -- of unobtainium, and then it gets interesting. A panel man working on my car awhile ago got a quarter panel repair section to replace some of the area between a rear wheel arch and entry door and found the placement of the complex lines and curves there to be approximately correct, but the depth and distinction was insufficient in his view -- it was 'lazy', so he reworked it: everything was pretty much in the right places so he 'merely' deepened the figures and made the lines crisper and more distinct, using the originals on the other side as a guide. Amazing stuff; made me envious.
Sounds like you're in the same line of work. Good luck with the one you've got your hands on. The lore is that they are some of the last hand-built -- hand-finished? -- cars made by any sort of major manufacturer. The apparent lack of panel seams was accomplished not with hammer-welding, they say here, but with spotwelding followed by silver soldering and, I guess, lead. Replacement -- and I suppose the original -- engine hoods come about an inch oversized all around, and are trimmed to fit the constructed car, and then numbered to match. Oh: the hoods are one of five aluminum panels one the 113s. The front and rear lids, the two entry doors and the soft top well cover are all aluminum, to include the pretty serious frame structures in the doors, which are nice pieces of work.
Well, it sounds like it could be quite a project. On the other hand, floorboards are easy to get and probably no different than anything you've seen many times before. Luck and best wishes.
And now I see DaveB has weighed in with what may be the best course to take. At the very least, I think it's safe to say this is likely to become a very complicated experience for you and your friend. You're probably in the best place here for info, advice and support, but DaveB said it briefly and well.
