The Smokies! Are you in the shadow of the eclipse? I'm planning a trip in that general direction next month. Either to Clingman's done or a "secret" rest stop near Anderson sc. either is about 4 hours one way for me. It's going to be a very long day.
There has been much back and forth about which is better but I think all of them have merit. I've also heard from some folks with larger systems that they have had good results from large servo motors with encoder feedback, but that's a different thread entirely.
That nema 23 400 step motor looks nice. Too big for my small rig but on a larger one like that lx3 it may work out nicely. When you start getting into torque figures things branch out quickly due to all the choices out there. with a well balanced rig, the stepper basically needs to be able to overcome the stiction(static friction) of the bearings and the of the worm gear/hob, or the bearings and the gearhead, or the mount bushings and the belts...etc. In larger units inertia comes more into play as well.
The higher powered 1.7amp nema17 200 step motor is rated at 51 oz-in holding power, the 400step nema17 that I found (sadly) had the lighter 300ma coils and only around 25 oz-in ..[figures and rambling erased]
so in short, yeah...that monster should have plenty of pull for the big guy. Looking at that spreadsheet I posted might give you an idea of what speeds you can get depending on your final ratio. You might want to count the teeth on the existing gear in the lx3 to get some idea what ratio you need to get it to the right speed, and if this photo is any indication, you only need a couple to get things going. That's a line frequency(60hz) synchro timer with a gearhead in that thing.
You might be able to read the rotational speed of that motor if you have it out. RPM is usually on the side of the gear section.
Remounting the yoke on an equatorial angle(wedge) will take the rotation out of your photos. I think big yokes are Superior to gem mounts. No meridian flip is a big factor. This is a photo of one on a wedge mount. Your machinist could probably make you something for it, just a thought.
www.cloudynights.com/topic/497182-the-re...ic-–-meade-2080-lx3/ Getting somthing on the DEC axis might be a bit harder.
Hope all my late night rambling helps somehow.