74 Tsunami Deck Replacement?

[Al B]

Hello all - I'm looking at a 74 Tsunami with twin Chevy 250s. The engines have 50 hrs on them, rebuilt outdrives (Mercuiser), the hull/transom is in great condition... the only thing is a "spongy" deck. How big a project is it to replace it? What's a fair price to have someone do it for me?

Any help/info is GREATLY appreciated!