I was given a 72 Swinger and will be parting out soon after I get a few things off for myself. It has a set of 4" to 4 1/2" wheel adapters on it. What would these be worth OR - since I may go to 15" wheels on my 70 - are they safe to use and how do they effect offset/fitment issues ? I know 4" pattern, 15 inch wheels I would have to buy new from Stockton or Vintiques, thought it'd be cheaper to use adapters and buy used 15's if it's acceptable. Thanks.