Just wondering how you line up the seals for the bulkhead and windscreen, and also the roof to windscreen seal. Would clear mastic be ok the seal the bulkhead to wind screen.
go find a window fitter and beg some 8mm draught/sticky back foam off him - and dum dum the corners. You'll need 2 people to do it with ease, mastic will just mean it'll be an arse to get off the next time.