OK I've got a bit further with this, but as 971wright pointed out it is going to cost. The gears alone for this project, and I hope you are sitting down, is around £220. I hope to work on this price some what, but it will give me a set of gears that is 128:1 and has a 14kg for 15mins / hour service life. Now if only I can make sense of this.

Yours Simon M.