The freelander floorpan has good boxy sills running down the outside, and two very similar box sections running parallel, further into the car. These inner box sections are far enough apart to let a discovery chassis sit up in between them (with about 15mm clearence either side), and so my thoughts were to take the transmission tunnel out between these rails, and add RR/disco style bodymounts to the freelander sills. The front and rear inner wings can then be removed completely, although I would like to keep the rear floor and utliise the freebie fueltank... This line of thinking cam from lying underneath the Mrs's freelander with a tapemeasure, and comparing the discovery I had parked next to it... very useful!
These are very similar to my thoughts, but by buying one with a blown engine it should be cheaper than buying a good one...