the last time I put together a 6,000 key ring on a 386 it took three days & several Mb.
The MIT PGP keyserver now has new non-PGP based code to manage it's keyring of 20,000+ keys. Not sure if you can get the code, or how easy it'd be to adapt to a deployed usage, but presumably it's much more efficient.
How about code that goes out & fetches keys upon demand, al-la DNS? [1st pass thinking is there are too many holes in such a method, even if MIT's server could handle the real-time load...] -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433