I have an intake from a 1966 327. Part number 3905393. I am not that interested in a correctly numbered intake at this point. The one I have looks identical to the 3919803. Would it work/perform okay?
As long as it is the same configuration, meaning same carb holes size, it should work fine and is essentially the same as the noted correct intake. It may be a 1966 date, but it's application is for a 67 327 and 350 for Q-jet. If it is, in fact, a 66 intake, it would be for a Carter AFB, so make sure the secondary holes are larger as a Q-jet would be.
The casting says it is 67 Q-jet and the Q-jet was introduced in 1967.