My last project bike was a VB360. I left the Bing on because I had such a good run with a VR250 using the same.
Some Say that the engine performs better with the Bing. I had no complaints, just flood like crazy, and kick twice.
I picked up a new? Bing ex US 18 months ago for $US120 on ebay, and jetted to suit the Montesa. Went great though with the old carb(no choke lever), just had to remember to turn off the fuel tap EVERY TIME, or a big pool of gas on the ground.