Me too ... I was a lousy student (in the early '80s) and then scored well on the Comp Sci GRE in 1990. I'm wondering whether they'll see the change I recognized in myself during that span.
I'm surprised they recognize GRE scores from that long ago. Anyways, good luck and if you don't get accepted try taking a couple of graduate-level courses somewhere else, or maybe there as a non-degree student if they allow it. Doing well would show your current academic capability, which is probably more meaningful to admissions.
I'm curious about your GRE comment - I took the GRE in 2007, and did well, and thus would like to include it in my application, but ETS says GRE scores are only valid for 5 years.
But other than Coursera and employee development, those GREs are the last academic record I have. You would think my transcripts from '85 would be even less relevant with that line of reasoning, but that might be exactly what keeps me from enrolling.