I think I recall some recent discussion about cabin heat boxes/valves  but sorry to say, didn't pay close attention. But now, having decided  to trash the hokey Lancair option, would appreciate suggestions for a  good stainless alternative. Needless to say, space is at a premium. I  have already made an opening in the firewall on the pilot side,  centered between and just above the tops of the rudder pedals and  just below the header tank. Aircraft Spruce shows several. I'm  gettin' too old to reinvent the wheel, so thought I would plumb the  depths of wisdom here. ):

Angier Ames
N4ZQ...still building