Thanks for your input on the jigs. The Avonside jig does look very good and maybe what I need.
Yes, I do realise a 9F is a bit ambitious, but I just love them! I'm already contemplating a second. The model I have is the DJH version, and when I bought it some years back, I also bought the Alan Gibson milled frames and some scale wheels. As for your question re sprung or compensated chassis, it may not make a difference given my end aim for this one at least. To be ruthlessly honest, my interest is much more in building very precise scale replicas, and probably less so engines that are acually powered and run! Maybe that is a sin to admit on a forum like this, but discovering the P4 community was something of great interest due to the true scale results and precision needed. I dont have the time and space to build and run any sort of layout, although I will at least build some track to display the engines on. It may develop further, I honestly don't know. Perhaps if I met up with a local group, I would be inspired to build a running engine on a club layout.
So although for this first attempt I will strive for as much precision as possible, the complexity of the 9F is dilluted somewhat by my own needs perhaps? I have also seen the Dave Bradwell chassis and I am very tempted. When I enquired about it he replied stating "that should keep you busy for a while"! For the moment I have some references and good photos, but I would love to see some drawings of the chassis itself.
So this 9F is destined to be as near a replica as I can achieve in this scale. The finish I plan is a very late service and heavily worn and weathered machine. I've practiced such techniques in my earlier modelling days, just never on a locomotive!
There are a few other engines in the growing store now and when I get a bit further on the 9F I may start a second. I have been very inspired by the books by Tim Rice, Guy Williams and Tim Shakleton and the bug has bitten very hard!