Well, that didn't happen. Got sidetracked with the scenario map itself (needed to track down a nasty little bug, among other things) and with other locos to go with these two.
The good news is other locos, as well as the 8 Class, shouldn't be far away. I've found that although the spreadsheets are good for number-crunching of stats, the effects of distance between stations and actual terrain means stats that might seem theoretically perfect when calculated often need slight adjustment for overall balance. This obviously means getting things running and testing them is the way to go.
I already have the 6N Class 4-4-0T ready for export, and will probably give it a test run tonight. This isn't 100% finished for detailing, but is certainly close enough to try it live and see what else needs doing.
I'm finding the NSWGR locos in this period to be particularly easy and enjoyable to build and skin. All of them seem to work very nicely at a scale of 30 pixels per RT3 unit (IOW, 3 pixels per inch at full scale). This is a nice scale to work with because:
a/ it gives enough resolution for really good detailing, and
b/ it's easy on the brain, since multiplying and dividing by three is generally not difficult, so calculating sizes and positions of things for accuracy takes little time, and
c/ since they all work at the same scale, relevant parts and layer styles can be transferred between models to save time.
Some less critical components are being done at 20px/RT3 unit to save space on the image, but only where the lower resolution won't be noticeable. That's the same scale as the Pennsy H3, so still not too gruesome.
One thing I have noticed is that slight adjustments to layer styles can make a big difference. Take rivets as an example. A layer style that works well at 30px/RT3 unit won't work at 20px/RT3 unit. The latter rivets have to use a smaller brush to look right, and that messes with the layer styles because past a certain point there simply aren't enough pixels for the same style to work. However, by changing the angle of the light source for those particular rivets (and leaving the others alone) it seems to be possible to get them all looking good. It just comes down to trying a few things (ok, a lot of things) and seeing what works and what doesn't.