Percy. Thanks for posting. Don't be afraid. No one here bites.
Those IDF's likely will bring some bucks here in the US if you choose to separate yourself from them. They are from an era before the use of personal computers so it is unlikely that any states DMV's would have a cross reference to the Porsche that they were stolen from now.
There are lots of "custom" intake manifolds made to mount multiple Italian carburetors still in existence here. They are almost entirely made for custom street rods, heavily chromed and largely trailered around from show to show.
Some need winches on the trailers to pull them on and off since most won't even idle the engine.
I'm not sure which came first, the chicken or the egg? The point of using IDA's on V8 engines is a plan to use independent runner manifolds. I'm not sure if the concept understood that reversion was going to be an issue, that the extent of the issue was not known or if it was thought that it could just be managed to the point of non-existence initially?
Certainly the existence of the Boss 302 dual Holley Dominator manifold suggests that there was a thought that reversion was not going to be any kind of an issue on a race car? In reality, that was/is just not so. The inside of the Boss's hood gets soaked with atomized fuel and there have been attempts to channel that fuel to a location in the engine compartment where it would not be a fire hazard.
IF you start to look at intake manifold designs that were built and heavily used on '60s race cars, you will start to see that there was thought put to how can you have IR manifold benefits and retain a common plenum at the same time.
Certainly my C60A dual four Holley manifold CLEARLY shows that hybrid design characteristics.
The point of the IDA's was simply that they were small, compact and lend themselves well enough to an intake manifold design that would permit each cylinder to have it's own individual carburetor and that their throttles could be located at the optimum length to the intake valve. Thought to be right around 4.5".
So to the non-induction engineering inclined folks it absolutely looks like you can create any kind of an Alien device and IT WILL WORK! I think that saying in this case, "a little knowledge is dangerous" is more then appropriate?