Public IPs routing question

Hi, i need to ask for an advice.

We need to provide Layer 2 connectivity and public static IPs for an organization that will have its remote buildings connected via our wireless network (192.168.0.0/16). Connectivity only, they will provide the Internet themselves.

(ORG network) ↔ ORG NCC (inside major ISP) ↔ Our Network ↔ Buildings

The first part seems easy - EoIP tunnels from their buildings to our router inside their NCC.
The problem is with the public IPs, we need to supply them, but i cannot figure out how to get them to ‘appear’ at their NCC so i can use them. We only have 3 IP/gateway pairs, supplied by our ISPs at completely different place. Should I talk to the “major ISP” to supply and route IPs to the point of connection, or should i talk to one of our peers, which has an AS?

Thanks in advance
Todor