Downside- Having a case combine behind that Deere header...
No seriously though, someone on here mounted a 635F to an 8010 and showed pictures of what he did, have a look through the past posts a few pages and see if you can find it, or maybe someone else would have the link?
i know a guy who is running the new style deer heads on his 8120 he has two of them set up that way. he likes the job it is doing he prefers the red machine but like the green heads. harvs farm supply can get you a adapter to do this or if you are handy with a welder and torch you could adapt it over yourself. with the variable speed feeder house drive speed should not be a problem
We run a 1293 corn head on our 8010. It works fine. We bought the kit from clarke machine in Howard, SD. All it is it a plate that bolts to the bottom of the header so you can lock it on the 8010. We also welded two pieces on the top so that it gets picked up on center. Very easy to do.
For the head drive, we replaced the yoke on the shaft to fit the 8010. The speed is fine, although we may have changed sprockets before, we ran it on a 2188. I can't remember. But a neighbor also uses 8010 on 1293 and i don't believe they changed any sprockets. The kit that bolts on does require you to cut off the two brackets where deere's pins lock the head on. If you were to ever put it back on a deere, you would need a bolt on bracket similar to the 8010 one, or weld those brackets back on.
We run two 1293s,608c, and a 630 hydraflex on 7120s. All shop fit, make the feeder fit the hole, wedge the bottom about 2-2.5 inches and fill in open vertical space between feeder and header. We use Headsight for comunication between red and green. Like the JD Hydraflex over the red heads