Ibanez Les Pauls didn't say "Gibson" or "Les Paul Model" on them, as far as i've been able to determine. They had the script "Ibanez" logo on them and nothing else, or they had the diamond pattern if it was a Custom.
I can't see that being just a Gibson neck on an Ibanez body... you don't get mis-matches like that on set-neck instruments, because dovetail joints are finicky things, and you'd have to refinish the whole guitar.
It's either a real Gibson, or somebody has had the headstock face stripped and re-inlaid with the Gibson logo and the Les Paul decal. If it's a Gibson, it's a decent price... if not, i wouldn't bother.