Just a heads up here. I'm not sure what the OEM HT master cylinder specs are but here is what I have found.
The master cylinder that came off of our M16A1 HT, maybe they vary depending on projected vehicle load, or maybe some one replaced it with the wrong one 20 years ago, is a 1.5" bore.
The unit I ordered from the part number sheet provided on the eBay "don't buy this" ad and the number above, is 1.25"
So, I'm going to give it a try, worst case I guess we don't get enough fluid and the pedal travels to the end and I find a 1.5" alternative, Best case scenario I'll have 30% more brake power and might be able to skip the booster.