It's not the same as the Right To Bear Arms lower shown in that link. There's too many differences. It is an 80% lower though.
Is it worth building? That's really subjective because generally 308 ARs are on the heavy side. Now a days Ruger makes small frame 308 ARs and they're much lighter. It's just a preference.
Upper receivers are really easy to assemble piece by piece. You just have to be sure the parts are DPMS pattern compatible.
Is there a blueprint sheet that i could use to see wat parts i would need to get? im guessing its cheaper to build piece by piece then buy a complete upper