The 200 series had some folding and some not depending on the age. Along with the split doors. If not, hinged replacements are common at such places as The Old Sodbury Sortout nr Newbury. £5 for the pair and presto the screen folds.....Although I can't remember about the wipers sitting here! No, it won't just drop forward if the roof is unbolted (easy if all the bolts undo). It is held with two turn down bolts on the bottom corners. Other parts will fit as they are common, in particular the army 90 rag top clips that hold the canvas to the screen etc. It is just a question of finding a good stockist. I can recommend Dingocroft in High Wycombe as I get my spares from them (business relationship only)
I think the only snag would be the one piece doors with the roll down windows as the top frame would not be removable. The door could be removed completely and perhaps replaced with a chain to stop occupants falling out! Split doors are a rarity for this reason.
An ex army 90 non turbo is a slow old thing but interestingly when driving a friends out of London along The Embankment last year with the headlights on some vehicles moved out of the way!! And no it was not my terrible driving!
If you do not do long journeys and do not want to get somewhere in a hurry I would consider an ex army rag top 90 as they are common, cheap and usually in reasonable condition. The gearboxes do not suffer with the problems that their more powerful cousins have especially the high milers say 140,000+ ie a rebulid with £500 worth of parts alone without labour.
But, horses for courses. Hope this helps a little...
PS. The 200 engine was the best apart from doing the timing belt! S
"Why,sometimes i've believed as many as six impossible things before breakfast"
The White Queen. Alice Through the Looking-Glass.