Does anyone have an understanding of what differences there are among the CDI units installed on Honda's TRX300's of various years? I notice that although they look interchangable among years the aftermarket CDI's available don't cover all of the years the TRX300 was made. Does that mean the OEM ones don't always swap out clean?

I've got a 1988 model that I've been reconditioning the last few months. The CDI was dead when I got it so I bought one off ebay from a newer model (1998). I've got the thing runnning fine except the thing starts missing if you rev it passed a certain RPM. Much like a rev-limiter does but this is well below the redline of the engine. I've confirmed it's something in the ignition through various methods...I have swapped out the coil and it had no effect on the problem which tells me it's not the coil. Since the original CDI was dead - I can't swap/test that.....and I don't wanna buy another one unless I can confirm it's the problem.
The original CDI and the one I replaced it with look identical...but are 10 years different in age....
Does anyone agree with me that the CDI is the likely culprit?