why a surface vessel to begin with? A large surface vessel would last exactly one engagement at most. It reflects radar, travels on the surface and is generally unarmored and would not have sufficient defences to stop an even half hearted attack.
Buy a Kilo sub off some dodgy Russian arms dealer, or even ask the Iranians if you could borrow one of theirs. With a competent crew you could last several engagements, and if you had a supply vessel or an out of the way base then you could probably last even longer