You might want to look at the Cessna120-140.org site - Forum -Parts for Sale. That is where I found the majority of the parts for my conversion - although it took about a year. Another good source turned out to be Copper River Airmotive - crairmotive.com 907-822-4004 - in central Alaska. A used Scott 3200 tail wheel in good condition is very difficult to find - they had them at "reasonable" cost - and some 140 parts too. Nice folks.
My 1963 onversion took to the air yesterday morning. It will be at home in her hanger Thursday night. Good luck, feel free to ask if you have questions.