Good call Bob, I remember seeing the other day that Halogens are still being produced and thought they might be the ticket for hot boxes. Although I maintain that as long as you use the same amount of total watts, it shouldn't matter if you use CFL or incandescent or halogen ... only downside is that turnign the CFLs on and off will reduce their life some. Sry to hijack.
Trux is right though, as long as you choose the stack thickness accordingly you should be able to make it shorter. Also, Kenny M has a nice design for a RD longbow that I think is 58/60 and 62/64" and all the matl's needed to build.