mega transmission line speaker

i think i have now decided on what to build this coming winter and will consist of the following. these are the units per speaker. 2 x b139 kef, 2 x b110 kef lower midrange, 2 x to be decided upper midrange, 2 x t27 tweeter, 1 x fountec neo cd3 ribbon upper tweeter. The reason for utilising kef speakers is that i have a pair of concertos and should be able to source another pair or purchase the other components individually. I would appreciate any suggestions for the upper midrange units that would be suitable.If anyone has kef units they no longer require i would like to hear from them.The box design will be based on the original c j rogers design.
I'd think that with the B139s and B110s, a WWMTM with a tweeter you can get down to 2-2.5k would be a better bet. T27s are pretty easy to sell and they could help fund the tweeters. B128 to B110 at 200-250 Hz.

The MTM could be grafted onto the slanted edge of the moderm TL Scott & i did up for the B139 -- the one shown in push-push guise. You might want to make the cabinet wider or ryn the B110s as a 0.5 system, to oush baffle step down to the XO with the B139s (would also allow you to move the tweeter XO up a bit)