I have the same problem with 504 - I have been stuck on it for over week. Essentially, as I see it, there are 3 ways to beat it:
1) Insanely good luck 2) Boosts (which will require money or unending patience) 3) Gold (which will require money)
I believe that this kind of level is designed specifically to push player into spending money on the game. I don't object to spending on the game and have done so, but I absolutely refuse to be strong-armed into it by a level that is deliberately designed to be close to impossible without spending.
Please don't link a video of someone completing it as I have problems believing that there are a bunch of people happily videoing all of their game sessions and uploading videos to You Tube. Even if there are people doing so, it is highly unlikely that I will get the same configuration as them and so the video is, in real terms, not much help at all.
Note: I find it far more likely that developers, who are able to manipulate the game configurations for a desired result, are making and uploading videos. I apologize for my cynicism but I can see no reason that King would deliberately create/change a level so that it is not just difficult but is impossible without incredible luck. Skill is almost irrelevant on this level - it is all about the initial layout and the drops.
Needless to say, I am getting tired of this level and will probably simply stop playing (and, thus, stop buying packs) rather than having to endure the same level ad nauseam.
I just want to make it clear to any devs/staff here that making levels that are close to impossible is a great way to drive away your players ... and your income.