you really should invest in a john deere 6620 turbo, ot maybe oven a 7720 both of these are excellent and i havent ever really heard anything bad about them
Went to IH rotor(1440) from 750, best move I've made in awhile.Capacity about the same but more reliable and parts are avalible.I have ran Masseys for a long time and have lot of spare parts that I would like to move, also a 78 hydro 750 with a 18' flex that runs good. Shoot me a email if intrested, I'm in north mid TN.
The JD conventionals (20 series) are not exactly any easier to work on than the honorable old 750_760s. They were a fairly reliable machine, but with the age they're at today, anything can happen... anytime. The IH rotaries are simpler, but many things are underbuilt. The old MF conventional, say what you will, was a tough act to beat back in the day.
You have lots of knowledge about MF combines that will be wasted if you buy a JD or IHC. Why not find a low hour 850. They are a super combine and will give you lots of good service. You could use your corn head and save money there too. Another option would be a grey cab 750. I have one of them for our second combine and it does a real good job. Good luck.