Bill makes some really nice horns ey. Its cool your building your own though, you'll feel really good about them when you finally get it to work exactly as you wanted. I know I did when I finally got my midrange horn to work properly after three different prototypes and hours of experimenting with various things like front and back chambers, phase plugs, throat size, etc.

Why don't you want to use any resistors in your crossover network?

Perhaps you could benefit from Waynes compensation network on your magnavox horns seeing as you say your missing out some of the top end. I guess you cant really know until you take a few freq response measurements on-axis. Use Speakerworkshop.

Adrian