Many Questions - New Project

I have pretty much worked out what I want.
The question is what is the best outcome I can achieve.
I have only owned one bug before & loved it, 1973 Superbug.
Prefer the earlier models now, pre 1968.

Hoping for a guiding hand from the well informed.

I would like to start with a clean body shell, the latest model possible that will still look very early.
I would like to fit a split rear or oval window if the body shape is the same.
I am going for a small chop top, rag top & suicide doors with no upper window frames.
Old style wheels etc but want discs all round.
I want to start with bare body for the mods & purchase a complete car later & swap the bodies etc.

Q. Are bodies all the same upto 1968, to me that's when they look like they change.
Q. What year guards are interchangable.
Q. What's the latest chassis that would fit this body.
Q. Can you fit late model brakes to earlier chassis etc.
Q. Do squareback chassis fit beetle bodies.
Q. Do all motors / trans fit any chassis etc.

I don't mind fabricating bits & pieces if required & getting engieers involved to achieve the result but ultimately want to keep it as simple as possible.

Any help appreciated.