Anyone place Lionel LCS sensor in curved track?

I think your approach to stripping the ties from an Atlas section and fitting it on top of a rail-less Sensor Track will work fine.  The IP ports on the Sensor Track are close to the middle rail, but IRV2 sleds have their ports midway between the center and outside rail so (apparently) the positioning of the ports within the rails is not critical.  As close as feasible to the center rail is recommended and you have to be able to push the programming buttons.  Slide the Sensor Track as needed to get ports and buttons to their best position.  (If you have an Apple device, the HighRail App is very nice for remote programming of Sensor Tracks).  Please post a photo of your work.

I put one of the IRV sensors into Gargraves flex on a curve.  The curve is fairly wide, certainly wider than O72.  However, based on the position and sensitivity of the sensors, I don't see a big issue with O72.

I did it previously on O-72 fastrack curve. Definitely put to the inside of the curve because of where most engines and cars with IR LED transmitters is located, they tend to hang to the inside of the curve. I stupidly first put mine in the gap on the outside of the center rail- relative to the curve and most transmitters didn't work or were intermittent.