I did this ride as an event in about 2000. I was lucky enough to get in with a nice group including the late, great Mick Potts and the inimitable Dave Yates. I enjoyed the ride, but remember the route as being quite complicated (apart from the bit where Mick said, "Well, I'm going down the A1, you lot can come if you want."
Have you thought about doing a DIY 600 instead? Make your own route, as simple as you want, chose your own scenery, etc.
Good luck whatever way you decide to go.