Sorry Neil, I was called away.... I have been asked a few times on how I scale up a project, I hope this helps.
Here is how I scale up a project, I must say though that it is the quick and dirt way... There are folks on this site who do things to a high degree of scale.
I try and pick a project that is a size that all the operating equipment will fit into. ( motors, servo's, hyd's ). To confirm the size I look for a brochere, like the one below.
http://www.komatsuamerica.com/viewch...id=927&chart=1