I only researched CDI night and day for about six months trying to come up with a programmable CDI I could build myself and have it reasonably reliable, resonably priced and able to perform to 13,000 rpm. I gave up.
Discovered my time was much better spent working and just buying a freakin system.
Anyway...for the CB125 you'll want to first check out some Honda two stroke dirt bikes to find one that shares a similar crankshaft taper to the CB125. Then see if it's feasible to run the 2 stroke rotor and stator on the CB (isolated from oil or not). A 2 stroke CDI is going to fire every rotation...no biggie, you'll just have a wasted spark. However you won't have lights since the mag/cdi used on most dirt bikes doesn't have a lighting coil
Unless you are racing the bike you'd be way better off just doing and electronic conversion to the points.
If you are racing...the easiest route will be a PVL system of some sort if you can't find a dirt bike system that will work.