It's probably CSB, not CBG...which usually looks the same in photos, because the green pigment was beyond fade-prone. That muffler is a K1 and has one of the threaded mounts missing(!).
The ironic part of all this is the fact that it's probably an original 3-speed with the original motor...which makes it worth more than a 4-speed that's missing the original (4-speed) motor, a 3-speed substituted. Further, the obviously slapped-on decals are more likely a plus than a minus. Looks like K0 decals could be reinstalled. Subtract the incorrect exhaust, decals and cheeeeeeeeeeeezy seat (that's probably
) and what's left might be a decent $600-800 bike, worth restoring...or using mostly as-is. Might even be able to sell the now-pricey K1 muffler for enough money to replace the AWOL airbox.
Oh...and lose the useless ST70 lift handle. It doesn't belong on a CT70.