Can you post scans of the cards? Even with the tape marks, it would most likely still be worth it to get the '55 Post graded. Even VERY low grade '55 Kahn's cards command a premium. From VCP:
PSA 3 Kluszewski $1,500
SGC 10 Kluszewski $411.25
SGC 20 McMillan $763.75
As for your '56's:
PSA 1 Art Fowler $49.95
PSA 4 Ray Jablonski $72.28
PSA 1 Johnny Temple $21.38
Here's a scan of my '55 Post so people can see what it looks like:
