Congrats on the "new to you" bikes. I kinda like the GS450's too. Not sure what I'd do, probably like others have already said I'd get the "T" model running first, and then goto work on the "E" model.
1997 Yamaha Seca II - mostly stock, Oxford Sports Style Heated Grips, Barkbusters Blizzard Cold Weather Handguards, a Scottoiler vSystem chain oiler. My Mileage Tracker Page