MT121 top end ideas?

Hi guys, i'm building a pair of mt121. Have got the 12" horns done and am thinking about what's going above.
Has anyone actually built a cab containing the MT wooden flare, another small wooden flare for a 6 or an 8" cone, and a 1" comp on a horn?
Have seen nuff discussion about this but no actual pics or plans.
Would expect more pleasant sound from paper cone in say 600-5k range than prescribed solution of 2" comp crossed at 800 which i would need to use bullets or slots with to fill in 10-20k. Could then use DE250 above 6"/8" which seems to be noted as a pleasant and smooth sounding comp driver going up to 20k.
Have priced up 12"/2"/bullets and 12"/8inch/DE250 and cost is very similar.
It also seems likely I could mount the DE250 in the horn mouth of the 12" although I suppose I'd really want the 6/8 in there to get the whole vocal range in one place.
My boxes have come out with 535x295mm space above the 12" flare, 670mm depth.
I know the correct solution is probably to get some software and design summat, but I'm on a Mac and it's a battle!
Could someone let me know an approximate horn length and mouth area needed for horn loading down to 500Hz, a suitable throat area, and whether a simple straight flare will be suitable for the MT121 box in terms of dispersion? Or inform me kindly that horn design doesn't work this way :) it discombobulates me somewhat....

the dispersion on the limmper is much wider than the porn or mt122 if i remember rightly?

and it's the wrong size and layout, but cheers anyway :) reckon i could cut it in half allowing me to put the 2 horns side by side rather than having the 1 above the 6?
What horn parameter/s affects dispersion? throat size and shape mostly? or does every variable have an effect?
and presumably my earlier request for basic design parameters can't be met? Do I need to decide on a driver first?
come on lads let's push things forward (i build my boxes with wheels on innit )

id say a 6" or dual 6" with a phase bung and bullets atop that would sound super nice, and was thinking of that myself for the future 8 & 12 i wouldve taught would have a lot of still usable frequency band which they both covered so a 6" would be more suitable and play higher meaning no comp necessary and you can just go straight to bullets, think HBL has a rough plan of this so might be worth asking him though finding a 6" you like the look of i would've said was priority 1

all things considered that sounds like a great idea now where did deadbeat post that bit on bungs...
 http://www.speakerplans.com/forum/forum_posts.asp?TID=13054&PN=4,
 better explanation than i could give on exactly this idea... good luck and when your done ill have to acquire the plans off you 

Edited by sKs01 - 16 July 2008 at 7:56pm

pics:
the front of the cab as it is now

with its lid off showing where this new little horn has to fit

side view

BREAKING WOOD MAKES MATT ANGRY. VERY ANGRY!!!!