Probably your best option, cost wise would be an Align Trex 500.
They arent much more to build than a 450, but almost twice the size. And if you go with say an MD500 fuse...it would be even larger than the typical pod canopy and boom.
However, since the MD 500 fuse makes any pod/boom heli appear to be much much larger...you could probably get by with a 450. My recommendation still is for the 500. The 500 is just a real nice flyer that is stable and large.
Google up some MD500 fuse and Trex 500 pics.