[dsraven]

nice job pella.looks factory.
the complete dash comes out fairly easily but the window needs to be out to access the spot welds in the seam. it may be easier to section it like you say. you could also raise it a bit so there is more room for the stg column and knees getting in. don't forget to leave room between the stg wheel and the finished dash for knuckles when you are turning and also room for feet and shins under the dash.
post up some pics from the side with the door open so we can see what you are dealing with. maybe come up with some ideas for you.
you could try a boat shop for a heater outlet, they use them in tournament boats all the time and they fit onto the end of a duct tube, are adjustable for flow direction and some have shut off valves to stop air flow. simple screw on devices mostly. they come in black or chrome plastic I think. they don't stick out from the dash a whole bunch either.