The 140B was my spolution to more brightness when I tried the Evah Pirazzi Weich. Not that much more, but more. The regular Evahs are darker than the Evah Weich. Both Evahs have more tension than 140B.
I never tried the Belcanto. Steels trings are generally thinner than synthetic core strings, at least for the higher strings. I play a high C, tried about 10 different steel strings and disliked them all for the small diameter (hard to press down in thump position).
If you are willing to give up the highs for more midrange you can try the Innovation 140H. A bit more tension (probably similar to Evah Weich), a bit more aggressive, sounds a bit like a simulation of a wound gut string.
If you want to stick with synthetic core to get a larger diameter than a steel string try the Velvet Compas 180. You need to bow well, because the more brightness will make bowing failures very obvious. But these strings cost more than twice as much as the 140B.
The reason I never tried the Belcanto is that they don't make a Belcanto high C. And probably my high C steel string experience. My problems with stel high C are that they are too thin in thump position to be pressed down successfully and they often don't sound good in lower positions.
It seems that you cannot have both, good sound in lower and in upper positions. Since the steels were too thin for me I decided to try the (few) synthetic core options and live with the shorter sustain in higher positions. I probably don't have much experience with your problem because I just play that stuff on my high C string (still a development string and not the last word, I didn't like the regular aluminium wound high C together with the standard set). But if you need something brighter than 140B you need to look out for a solid core synthetic string like Innovation 140H (medium low tension) or Pirastro Obligato (medium high tension).
For me the best medium bright arco and pizz string is the Velvet Compas 180. But expensive and needs a lot of care to mount them correctly. If you need them a bit lower tension there is a SUIT set that sounds similar with just a little bit less power.
