I like the idea of building from what you already have though it favors the hoarders among us (e.g., me). Maybe allow a two-week (14 day!) window to acquire additional items?

I have several candidate frames hanging in the basement:

—70s Jeunet, which I had built up with 650b x 38mm wheels
—‘85 Raleigh Gran Course, fits 28mm tires
—Carver Ti frame, fits 35mm tires