this is one of those cases that disproves the rule about red backgrounds. in this piece, it neither overpowers the subject nor blends in too much with his skin tones. you've found the magic balance. nice work.
The final rendering on Stan is terrific, and the 60s'/70s' lettering style is just perfect. While I liked the original red background, I think the change to blue was the right decision - it helps the shirt pop more.
My only little gripe is that I feel the background is a tad fussy. I think it would be stronger getting rid of the white Kirby dot pattern and keeping just the black ones. It would feel more Stan-era authentic, in my opinion.