+1 on the Signature Cycles. Top notch operation. As dendawg says, plan on spending 3 hours on a fit. They don't shortcut anything. As I recall, $375 and $175 or $200 rebated if you buy a custom frame from them. In reality, that is a small component of the cost of a Serotta --as least it was in the case of my Legend Ti . . . .
Signature will also do a fit check on an existing ride and make necessary recommendations as OP requests for a lesser fee.
A number of NYCC folks speak well of Mike Sherry. I don't have the contact, but maybe track that one down.