I want to play as a Dragon.

[Umbranis]

Let me start by saying that this is an END GAME CONCEPT, obviously I don't wish to start a game and be a dragon going around with a party of heroes, and socially that could be awkward. I'm thinking more along the lines of stealing a dragon's body through methods similar to Magic Jar. But alas for me to make this plan into a reality I would need more system mastery than it appears that I have. In this state I turn to the message boards and ask very simply can it be done in PAIZO PRODUCED PRODUCT ONLY? I'm not talking about imitation of Dragons through Sorcerer Bloodlines, Dragon Disciple, or Bloodrager/Magus wonky builds.

I thought I found my first solution with the spell Embody, but it was a 3PP. Magic Jar seemed promising, but again it is a spell that would not allow me access to the breath weapon, or other special abilities even those associated with the exceptional body. So help me find a way.

[Bearserk]

Start with a Wyveran....and grow! ^^

[Gray Warden]

Just go Bloodrager or Sorcerer + Dragon Disciple. Of course you won't be able to stay in dragon form permanently, however.

[Anguish]

A few applications of wish should suffice.

[Ten'shun the Tengu]

Form of Dragon + permanency? It'd be a small stretch for a DM to let that pass.

[Dwarftr]

The new Legacy of Dragons book has some useful tools that could help you on your way. I only got to glance at it but there are good options in there

[Carl Harris]

For that matter a Polymorph Any Object would suffice, but this effect seems beyond the capabilities of limited wish.

[Rayek]

Even though you said no 3rd party material you might want to have a look at "In the company of dragons".
It contains a new race, the Taninim, which basically are true dragons, a new racial paragon class, with draconic class features and innate growth(start small and grow one category every 4 lvls), or rules to use paizo classes, sacrificing some abilities for growth.
I have only played the paragon class for like 6 Lvls, but it is pretty balanced.
You do get 3 natural attacks from the start, but you cannot wear armor effectivly. You get some natural armor to put up with that, but will lack in AC.

The "legacy of dragons" book has many classes with draconic features and the option to get a dragon as animal companion, but no option to play a true dragon.

[Quintain]

There is a new product from Dreamscarred Press in their Monster Classes line that makes dragons into a class.