I had the intention to source the components myself already. Just waiting for the build list to be updated with all the needed parts so I don't have to search too much.
I'm not entirely sure we're talking about the same thing, so at the risk of re-stating the obvious, let me try to clarify. What you have contributed to so far is the overall project, and will presumably be assembling an ARGUS prototype. With these boards, one has the option to have no ROM, installing a 1 MiB ROM in the provided footprint or installing an additional ROM module via headers installed in place of the SOP44 IC and X3. I was referring to the third option, which I expect will be a separate, extra-cost option in the final run.
The hardware is currently in a pre-prototype proof-of-concept state. I tried following shock__'s measurements exactly, but there is even some possibility that the board won't fit at all. Furthermore, since I expect interest will be relatively low, I opted to contact only a couple of people directly to ask about their willingness to test the additional hardware. Between the ICs, headers and connectors, it gets too expensive to give them away for testing. To avoid the additional cost, I expect most people will make other arrangements.
So, to make a long story short, only people who end up with the additional boards will be able to test the larger ROM images.