Seems almost a transitional between his earlier versus later graphs. I know it's not a secretarial so. I also look for a slightly tilted left "L". It's got his oblong "P". I assume hastily signed. There is enough positives for me to say it's likely authentic. If I was an authenticator(thank God I'm not!) I would give it a passing grade.
I guy who knew authentication once told me he went by the three strike rule. The OP does not have three strikes. IMHO.