That's one impressive collection he has there,
I'm not sure where Chris' knowledge of cards lies but here's a few things I've picked up from collecting
If he has a really good condition 1st edition Base charizard, he should get it PSA graded, grades 8-10 go for between £800-10000 each.
Also, it's worth checking the non first edition Base cards to see if they're 4th print, a 4th print Base card has 99-2000 date in the bottom right corner, these are worth significantly more than the normal counterparts.
If he has any others for sale can you let me know?
Edited, pricing was a bit off