I'm not familiar with "polytone" but I'd mention a friend who bought a Stinson last year. It was a good purchase at a good price (for what he got) but it is fabric of course, and had been painted with Imron.
While it's not bad to look at, the problem is there are cracks in the paint at certain curvatures and since it's painted with a polyurethane it cannot be easily repaired. It'll probably require complete recover.
So,....just be sure that what you use can be easily repaired, repainted, etc. in the future.
As for how much time to re-cover wings.....beeliner....I really cannot say. Too many variables exist....and I've never actually done a 170 wing. I wouldn't want to mislead you. The question is better addressed to our entire group, I think. How bout it guys. How long?
(Meanwhile, keep in mind you're going to need a couple of helpers to remove and reinstall the wings. After you have the wings on sawhorses, you can cut the old fabric off yourself. You can do all the cleanup of the interior yourself. You'll need a genuine,
qualified (that means not only someone licensed but also experienced in this kind of work) A&P/AI to inspect your structure and recommend needed repairs (if any) and you'll likely need someone to make those repairs (if any), then you'll be ready to do the actual fabric work. Up until this point, not including structural repairs, you've spent a little less than
two days, but allow for the full weekend. Two weeks of your own time after normal work hours should have them basically re-covered. Another two days to take care of the unforseen details, such as painting/replacing inspection covers, lighting issues, and trimming, and you should be ready to paint them (if you intend to paint.) That's another issue of course. Will you paint them? Or leave them silver primed? And can you do the painting? Do you have the equipment and locale for it? Or will you farm that out?
After those issues are resolved, your buddies will need to come back over for a weekend to re-install the wings and do the rigging.
Your A&P/AI will need to come inspect and do the paperwork, an issue standing entirely alone. Some A&P/AI's know their client's capabilities and tooling well enough to turn them pretty loose and come back later to do a final inspection/sign-off. Some don't and want to be present during the entire process. Find out what yours will expect and will charge you before you get too deep into this excersize. The FAR's require the A&P/AI to supervise the work to the extent necessary to determine that the end product is airworthy. How much experience you have and how much experience your A&P/AI has working with you may greatly influence how much direct supervision is required, ...and thereby how much time you will be charged. A Flat-Rate for the project may be an option you wish to pursue.)
Just a few considerations. Don't let the details bog you down. It's a good project for an owner, and it isn't as difficult as you might imagine. Good luck.