Here is what I'm thinking currently based on everyone comments;
Environmental control - Ability to work ~3 seasons to do priming / canopy fiberglass.
Basement - fullly meets needs
Garage - mostly meets needs, would need supplemental heat.
Space conversion cost / time - Conversion costs to / from workshop
Basement - somewhat meets; cost to remove french door twice; carpets pulled up, pool table relocated / sold.
Garage - Minimal conversion costs; popup camper ongoing relocation cost
Space availiabilty - best overall size / location
Baement - somewhat meets; due to hallway restriction of 3' can't get fusulage there, wings only. One effective workspace. Other one for storage.
Garage - mostly meets; minor inconvenience of pulling cars in/out. largest workspace 27' x 20'.
Fume containment - prevent fumes from entering the house
Basement - can't meet this; although not sure how big a deal this will be.
Garage - fully meets
At this point I'm thinking the following:
Garage - overall best location for building. Get a space heater or work around seasons for canopy / priming work. Put tools / equipment work tables on locking rollers for easy moving around. Easiest way to get from house to airport for final assembly.
Basement - use as storage solution for wings and staging area for parts. potential workshop for wings.
Final criteria is talking to the boss to see how this flies.
Thanks so much for everyone's perspective. Any final thoughts please post. And looking forward to contributing to the forum as I gain knowlege and experience with this journey. One more life accomplishment in progress from my bucket list.