I shoot new stuff, mine my hard disk and copy old slide material. Most gets accepted and one of my best sellers is from 35mm slide film shot in the mid 90's. Another great seller is from a 4x5" slide made in the late 80's. Copied them both on a D90 camera (no fancy schmancy Flextight scanners for me

). So, it's impossible to say what to do. If it's good (qualitatively and technically) and commercial, it should get in!