That shouldn't be the case if he's level 27.Is the CP at the end of the curve? If so, you need to wait until you level up again (lvl 28, in your case) as that will open up more levels for your Snorlax to power up to.
This has merit.Probably wasn't the best decision to power up a 419 Snorlax all the way up to 1.1k. Even if it did have perfect iv's, around 80% perfect iv's with a higher cp would've been a better option in hindsight.
I've tossed out a 98% IV (15/14/15) Dratini before because it was around CP170 and I'm level 30. It would take a godawful amount of Stardust and Dratini candy just to get a Dragonite of any respectable CP out of it, not to mention I can't even guarantee a good moveset. By the time I capture all those Dratini to obtain the necessary candy, chances are I'll probably end up catching a higher CP Dratini with similar IVs.