Make it a single front chainring and use a Hollowtech2 68mm BB then just use spacers to figure out your chainline. They still make 9, 10 and 11 speed freewheels. Most likely you would need 2 spacers on your drive side and one on your non-drive side. Super easy clean set up. Set it up with a derailleur hanger if you want more range and a more modern derailleur. I like to use one on each side with the non-drive side hanger as a spacer so the wheel stays even in the dropouts. Just grind the threaded part off and flip it. Is that a dent in the chainstay or is it like that on both sides?