Posted by Bill Chugg on 15/06/2018 06:31:47:
Posted by Neil Wyatt on 13/06/2018 19:31:17:
Is embarking on any 7 1/4" loco other than madness? 
Indeed an interesting comment.
Tongue in cheek, but embarking on any steam loco is a big commitment in terms of time and effort and those not part of the hobby would probably consider it rash, if not madness!
The serious point is if you are going to take one one, I don't think the implications of the actual gauge would be my first consideration in terms of difficulty. Up to 7 1/4" you should be able to tackle most jobs on ordinary hobby equipment (aside from big single wheeler drivers or milling out large frames) and the larger size may even make the work easier.
I would say the main consideration has to be the much cost of materials and especially a boiler.
Neil