It sounds like you may want to think in terms of "vault" rather than "safe". Finding something off-the-shelf with the volume you want and the security you're asking for is going to be tough; among other things, that sucker is going to be extremely heavy. Shipping in plates and constructing the box on site, then fitting a high-security door to it, may make more sense; the weight's still bad (check that your floor can handle it!) and you're now dealing with welding on site, but this gives you the flexibility in terms of protected space that you seem to be looking for.
Seriously, though: If you're willing to spend seriously money, you should hire a safe-and-vault expert to work with you on this, rather than asking here. Even though we do have some legitimate experts here, addressing a problem like yours is going to require sitting down and discussing *exactly* what your needs are and whether it is actually possible to address them for a price you're willing to pay.
Normally, I'd suggest that at this point you start talking to banks about storing your collection in their vault rather than building your own... but I somehow suspect that banks would be leery of storing firearms, even without ammunition.