Hi Bob, not sure if you saw this 72 Newell they were parting out a couple of years back, or if it is still around but may be worth a shot for some parts.
http://www.luxurycoachlifestyle.com/...72-newell.html as for the wheel cylinders you should be able to buy the cups and dust covers from a brake shop, in my opinion it would be best to at least find new seals.
If this newell is still kicking around it might be worth checking out, hope this helps!!