I routed my heater coolant lines thought the center tunnel up to a vacuum switched selector valve (so I can shut off flow of coolant to heater bu maintain loop through engine). Biggest concern I have considered is leaks drip into cabin. I figure some strategically placed drain holes might be smart so leaking coolant doesnt go far.
Love to hear thoughts from you all! If this approach is ok, I am another step closer to starting this thing up!
-Ben