Stainless Steel manifolds

[patp]

Hi my brother-in-law found a pair of almost new stainless steel manifolds made in the early 80's by stainless marine. They are for a BB chevy. I would love to use them but I have twin 454's so I need another set. The manifold and riser are one peace. If anyone knows where I might find a matching set the help would be appreciated.

Thanks