Hi Chris -
S'funny, but my old one behaved exactly the same way.
Worked great! After it cleared it's throat and sinuses.
Never did get it cleaned up, but I did not have the injectors redone - that might have helped. As I said, it worked great, so why spend the extra money! And after probably 5000 hours, the crank was still standard size.
Sold it two years ago, to standardize the fleet on Perkins.
The hard starting and smoking were probable reasons that Massey changed to Perkins. Plus a possible 15% increase in power. But none of my Perkins pass the first overhaul with standard cranks.
Can't have everything, I guess! The 35 is still probably the best tractor in it's HP class ever made - whatever motor it has. And parts are still available, cheaply from aftermarket sources, 45 years later.