I recently got an 1888 Davis machine that was originally in treadle that someone put a funky motor on in the 1930s (most likely from the paper I found with it). Just take the motor off and find a set of irons on eBay or Craigslist. It will happily be a treadle once again!!
Also, go on the Vintage Sewing Machines Virtual Page on here and look for Miriam's list of sources for information on restoring...I just read a lot of those yesterday and tackled my Davis last night with good result. There is a ton of information on the links she provided.
Good luck!! It's a fun project!!!