Interesting. You may have discovered another means of adjustment we didn't know about?!? Anyway...
I can find no listed torque for the pinion shaft nut that holds the drop arm. I think I used about 60ft/lbs, as I seem to remember that is when I was sure the drop arm no longer moved on the shaft. So long as the drop arm is secure, the lock tab will keep the nut from backing off. Most bolts are held by "stretch". Whenever a lock tab is provided, I assume the assembly is not torqued enough that bolt "stretch" will hold it together. In other words, I don't think it takes a large amount of torque on the nut, or the lock washer would not be needed. I say that because most American steering gear arms I have rebuilt used like 100-120ft/lbs. I don't think the little TR arm would take that kind of torque. Just me thinking, though.
As far as the 2" x 5/16" bolts. I would assume the standard 14-16flt/lbs. If that amount locks the steering pinion shaft from turning, then you have discovered another way to tighten a loose pinion bushing! Definitely don't tighten them to the point the shaft locks, up to a max of 14ft/lbs.
It sounds like you're about done with the steering gear rebuild. Can't wait to hear how the car drives when you're done!