Intel C1101A

Putting this out there for those hopefully in the know. I have been acquiring date-correct ICs and parts for my Mark-8 project, which is years down the line. I'm planning to build it on very carefully replicated clone boards, based off my originals. For my purposes, I'm trying to keep ICs early 1975 or earlier. Most Mark-8s that I've seen have P1101a plastic encapsulated RAMs. Most are Intel brand, but I've seen some that I think might be National or something.. they just say P1101A on top. The only source other than ebay that I have are those big chip vendors like Summit. And the problem with them is they aren't always precise about date codes. The P1101A, because they were produced for years, have a wide range of codes and the places I prospected them from couldn't guarantee 75 or prior. To my surprise, I found a few places had C1101A. They are white ceramic, gold legs. They have a 'batch code' of F1268. I got 16 of them for $14 each. I was going to get 32, but Summit also surprised me with 5 1973 vintage Signetics n8263s @ $25 each. I hadn't been able to find any pre-1980 so I snatched those.. but that put me beyond a budget where I could buy 32. I figured I'd buy 16 chips for now and then buy another 16 the next month. Now of course, the chip houses have turned tables on me. They want $48 per chip instead of $14 like last time. And checking around, that seems to be uniform. Now, I'm not averse to paying that, though it will sting. But I want to make sure my assumptions are correct.. that these white vintage ICs are in fact pre-76. Can anyone confirm that? The info out there is a little vague. And would it be totally out of place for C1101as to be on a Mark-8? Could a hobbyist have had a source for them, beyond having some lying around?