We put a 500 series head on our R5 last year, and we were looking at the same problem. We ended up getting some parts from salvage, and made the changes to the combine in order to power the reel from the combine. We needed the valve, and we also managed to get the auto speed module etc. thrown in on the deal. Took a little bit of wiring, etc., but it works well. The only problem we could identify would be that when you steer fairly fast, the reel or pickup will slow down, as the power steering is getting priority. Irv