I have a hh120 from a 1968 sears suburban ss12. The engine was locked up I took it apart to freshen it up. Decided to go the route of building a pulling tractor. Like I said im new to these engines and am absolutely clueless so all help will be appreciated. What other tecumseh engines will interchange parts with the hh120. Also some performance tips would be great, ive been researching for a few days now and have come up empty handed learning how to make any power and realizing that almost all engine parts are obsolete now days.