I can't answer your question Des but I'm sure someone else will. A couple of years ago I went to the All German Day at Canberra (quite a big day out) and there was a wonderful selection of beautifully preserved or restored Pontons.
Now, if you are to buy one you either buy the best there is available and bugger the expense or you restore one to the highest standard and bugger the expense. Do you want to do that? Or, do you want the 170? The real point is, buy what you want - not what we here suggest....
Regards,
Benzboy