This was another debated issue, but the prevailing sentiment on the Ford FE forum was that you should run the
oil pressure relief valve in the block even if you have a pressure relief valve in the
oil pump. As I recall, George Gessford posted a message to that effect stating that he did that because the "block was designed to use it." Other builders tended to agree with that, although it was not unanimous. I went to Gessford's site and he has them in stock. A phone call to him couldn't hurt, and here's the page on his site that has them.
http://www.gessford.com/cobraparts/fblocks.htm Please post your OP numbers when you fire it up as I am really curious to see what the results are! The fact that both the builder and you had good OP numbers before you put the engine in the car has me befuddled.
