I believe that Ike's pipes are a variation of Terry Cain's "Bigger is Better" design. If so, there has been a long thread at diyAudio Forums - Full Range. This is not a "Voigt Pipe", it is a folded back horn. I have problems with this design, but apparently it works well when placed against a wall, or better, when placed in a corner. Of your driver choices, the B200 is only suitable for open baffle applications. The FE126E might work, but the FE127E is a better choice. The Lowther D55 might work, but it is way out of your price range. I know nothing about the Tesla drivers.Do yourself a favor. Get a pair of FE167E's and put them in a proper MLTL. You will be happy with the result. The total cost of this DIY project is $200-300US, depending on the finish you apply, for parts purchased in the US. Talk to "Vintage_Dog".
Bob