There very well could be other issues, but on the subject of the flywheel shield rubbing - my 720 did that after I installed it's taperlok flywheel. I found threads here in the archives from other people having the same trouble after installing taperloks. The endplay was correct and all. I just put a washer behind the flywheel cover at each bolt and that fixed it.
Having said that, I would NOT buy that 70. A crankshaft of unknown quality is a deal breaker for sure with these. I've been through it all with this 720 of mine! Good used cranks are getting impossible to find. I finally found a guy with a N.O.S. crank after almost a year of looking. Then you can run into issues with mix and match main bearing housings, flywheel spacer, and thrust washers. On mine, some of those parts had been updated through the years and some had not, and it was not working! And this tractor ran good when I bought it.