Dont let the parts support scare you, There are still many parts for both Chassis and engines, although some of the HH/OH Tecumseh's are getting hard to find Connecting rods and pistons for but for the most part almost everything you would need is still available.
Engine pricing goes up every year on alot of the stuff but thats just how this industry is going but the fact that the OEM's like Wisconsin,Tecumseh and Kohler still offer parts support for a 50+ year old machine should make anyone happy regardless of cost. I'd rather have the option of paying X amount than hear "NLA" , i'll gladly put $$ into a old engine than buy an EPA regulated engine made today but thats just me.......