Joe !
I've seen your dwg and use the official macro :
_move;_all;;0,0,0;0,0,1e99;_move;_p;;0,0,0;0,0,-1e99;
The problem is that I used it on all objects and it spreat some of the red 3poly on the top to incredible points (at huge X and Y).
So, if we exept the problem withe those few elements that I finally removed before the macro, the macro seems to be convenient and fast. Don't know if you know it.