I guess you are looking for FACTORY? The only factory ones are for the Magnum heads, and the way they are constructed, I'm not sure you could adapt them. Bill Grissom, on here, was planning on trying.
So far as aftermarket, I'm planning on modifying my own. I have a low buck Torker, read down through this thread. You can buy the bungs, or use these pipe fittings.
http://www.forabodiesonly.com/mopar/showthread.php?t=198603
But the real point is these:
These are plumbing store 1/2 compression x 3/8 pipe fittings. For the Ferd injectors I have, I had to turn a few thou out of the inside. You could conceivable install these with a drill press. What you could do, for example, is to bolt a large piece of scrap plywood to the carb mount, in a fashion that is square with the two intake flanges, and then rig a fence on the press table to keep them all in line. Spacing front/ rear does not have to be exact, because you will make the rails, anyhow, so you can drill them to match.
You should be able to find a used Torker cheap, and they are ideal for port EFI
http://www.bangshift.com/forum/showthread.php/4410-El-Cheapo-Injector-Bungs
Another website I ran across, the person was using this type of pipe fitting, and turned the inside out to fit the injector. These fittings should be cheaper than the compression fittings, but will need more work to fit
