Larry I think you are correct on the manifold it was just a guess a bad one however the stems that the orifice are on since I have a Silver B manifold and a 1000 in the basement. I did a comparison took a block of wood covered the orifice hole and measured it back to the manifold. On the 1000 its about 2" on the Silver B manifold it's 1 5/8, Bobby said he was off around 1/2 inch short but it could be 3/8 who knows.
It would be easy for him to do the same thing on the old manifold and the Silver B that he plugged in. They only made that model for 2 years before they switched over and those valves I linked up above fit his model they don't fit the newer Silver B's and C's.
You are the king of conversions so since that was a premium model if he took out one of the valves to see if it was continuous and it was. Could he take the orifices out of the Silver B plug them into his old manifold and off he goes. I don't know if the orifices were different and whether that would work or not, I did notice on the silver b manifold they are a little flatter than the ones on the 1000 not sure if that makes any difference at all but I really don't know.