Head gaskets for performance engine use for 200 / 250 is a common topic. Here's an uncommon find - OEM D3xx Steel shim gaskets. The 144/170 gaskets are readily available but I've never seen them available for 200/250 .
http://cgi.ebay.com/ebaymotors/Ford-Mus ... ccessories
http://cgi.ebay.com/ebaymotors/Ford-Mus ... ccessories