No reason it won't work, but I've never heard of anybody doing it. Putting injector bungs in that intake manifold wouldn't be the most fun in the world. It would likely get you a little fuel economy, but no more power.
The big problem with boosting the efficiency of a straight six is the long intake manifold, which results in uneven cylinder filling and uneven mixture distribution. The solution is usually to go to a dual plane manifold or three little manifolds (like Jaguar did). As it's a flat head, you're not going to get a lot for your trouble - the compression ratio will always be low, and the chamber will always have a large surface area relative to the volume.
Flatheads are smooth, but they are not noted for great fuel economy or amazing power for a reason.