I recently had consistent derailments with 034" curved Gargraves. The easy solution was to remove the brake hose (which is arguably prototypical) and cut small notches inside the steps with an xacto knife. This allows the coupler to swing enough to stay in the center of the track on the tight curves. So 036" may or may not be a concern.
No problems with the matching 0-4-0 engines though.
