Visited Lowes and automotive stores this morning and got some miscellaneous items, so I continued on with the plumbing.
On the heater return port, I installed the adapter to the 45 degree hose stub as well as the 45 degree barb and one end of a heater hose. Fed that sub-assembly back into the engine and reconnected the elbow hose pointing the opposite direction from its original orientation so that the return hose points aft instead of forward. This lets the hose go under the intake manifold quite nicely with a short run to the firewall.
Could not find the gearbox translucent high temp tubing, so just got a length of normal fuel line and a straight line connector and extended the stub provided by Viking.
Temporarily positioned the heater and cut four 5 1/2" lengths of threaded rod. Drilled holes in the avionics shelf above the heater and used nuts to secure the heater unit back side. I was not able to locate high temp grommets locally, so ordered some for free pickup from Grainger. For final install, I will use lock nuts on the top and bottom exterior and jam nuts inside. The unit hangs down on the passenger side behind the map box shelf cutaway.
Began heater wiring. Added holes for 5A fuse and Viking provided double-throw switch for activating one or both sides of the fan. Also started wiring for the switch and breaker, but did not get finished.