According to the DS9 technical manuals this is the
CHIMERA CLASS CHIMERA CLASS If you went by scale being that it's an Excelsior model it would be just under 400M.But,according to DS9 it's listed at 288.33Meters.
So it could function as an FCL , FFF , or FHDW .
Chimera class
The LUG RPG supplement Ship Recognition Manual, Volume 1: The Ships of Starfleet calls this class a Fast Frigate (288m long, 15 decks, in service from 2366 - corrected to 2374 by a discussion board posting from the author, Steve Long) and makes it the triple nacelled Excelsior variant from the Deep Space Nine Technical Manual. Also listed are the U.S.S. Chimera NCC-71653, U.S.S. Ta'veret NCC-71777 and the U.S.S. Janeng NCC-72146; whilst The Dominion War Sourcebook: The Files of Armageddon mentions the U.S.S. Hephaestos NCC-73469. The Portland is not mentioned at all, combined with the dates and the registries makes this all seem a bit suspect.
NCC-57418 U.S.S. Portland
History: In service in 2371.
Notes: DS9 "The Die is Cast" ref.