1965 Cadillac Exhaust System

I've been having a terrible time locating anyone who can properly make the exhaust system parts for my Fleetwood Sixty Special. Apparently the IPC bend cards that seem to be in use are either wrong or are not sufficiently specific.

For example, the connector pipe between the resonator and the muffler is supposed to connect over the top of the resonator's connector while most shops make it fit inside. In fact, all down-flow connections must be done inside the previous for proper flow and to prevent forcing moisture into the seams.

Also, the connector pipe needs to be flattened down its length to clear the under-body braces. If not flattened, the system must be lowered a half inch or so to clear which often requires the use of aftermarket supports.

Does anyone have a source that actually knows how to make these as they should be or are there still reasonably-priced NOS parts around?