This is a tough one to pull off because his real life proportions are already extreme so his caricature could be pushed really far. Your likeness is good, it does come across as just a straight portrait.
By the way if you want to study some of the best caricature then take a look here http://paulmoyse.com/books/heads-shoulders-digital-version/
This is your strongest work. Immediately I knew it was Stallone. One suggestion is maybe his eyes could be more droopy. I'm sure you were faithful to your reference, however Stallone famously has very droopy eyes, so it may be helpful to draw from multiple references to be sure not to miss a key detail that will take your likeness to the next level.
Yeah, his famous sleepy eyes. LOL! Thanks for the tip.
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