IIRC Scountmasters don't use "armboards" like (most) Aries models. VPI arms are surface-mount. Many non-VPI arms route the cable down through the plinth and need a much larger hole drilled there, which could get messy on a Scoutmaster (MDF / vinyl and steel sandwich).
So, first decide if you have appetite for that or need to stick to a surface-mount arm. VPI makes a couple of gimbaled arms, but their upscale 3D-printed Fatboy's pricing is...ambitious. I'd stick with metal anyways.
In general, Jelco would be a fine choice. Sad they're now gone. Ortofon had a few upscale arm models made for them by Jelco in the past decade. These show up used occasionally, and I think they'd make a VERY nice choice, barring issues getting it onto your plinth.