Keith, I will be bringing parts to the FE Reunion so if you want to buy something there, just let me know and I'll bring it along. If you pay in advance you can avoid Pennsylvania state sales tax.
As far as the adapter, I think I would start with the #13004 if you want to stick with the 2V port size. You would have to put custom ports in, but it could be made to match up perfectly to the intake. The #13003 with the starter ports in it will have the starter ports a little too tall to work with the 351C 2V port. Alternatively you could just go with one of the standard #13001 adapters, and port the intake to match that. The #13001 adapter's ports aren't as big as a factory 351C 4V port, they are kind of half way between. Somewhere on the site is a picture of the port mismatch between a 2V intake like the Performer RPM and the #13001 intake adapter; if you can find that it would give you an idea of how much port matching would be required - Jay