Yep, I agree with Rusty, the crank seals go brittle, and the engine sucks the gearbox oil into the crankcases and suddenly the fuel/oil ratio goes from 25:1 to 10:1, and you can't see anything behind you and your two wheeled "Fogger". The 1972 J(?) model on eBay for $2800.00 is a much more desireable bike, like the GT750's, the first model is always the most collectable.
Having said all that, Magilla's bike is a nice looking bike, and I can respect his "Red paper Clip" bike buying/tidying/flipping regime, I've been doing the same thing over the last few months and it's great fun continually "trading up", if you don't have big cash reserves to just buy a nice bike and keep it. Realistically, I'd say $1500 might be a fairer price, considering it's a big job replacing the crank seals. Cheers, Terry.