Re: how the **** do you do this?
You'll benefit from designing and building a 'jig' to fabricate frames. That will give you known alignments to work with. Trying to 'eyeball' something as critical as forks and rear dropouts is asking for trouble.
My main concern is what is your welding experience?
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"