So,

I am working on a project to install early 911 trailing arms into a 356.
Instead of a full tube going from side to side, I need to built two shorter tubes to allow the larger transmission to fit properly.

The question is this.

Assume the tube is perfectly square within the chassis.

Would the mounting face of the wheel at the hub be perfectly square to the chassis with zero toe in our out?

Looking for a method to lay out the brackets to get it setup properly prior to welding.

If you can find a salvage yard with the suspension and drivetrain out the bracket layout would not be hard to measure out. Personally I would build the pivot mount box out of the car and then make adjustments as you go. The other option would be to find a wrecked 911 or one already cut in half and use it as a jig or remove the section you need and graft it to the pan.

If I could find a rear 911 or 912 tube, then it would buy it...trailing arms and all.

But I don't want a whole car....

I have called some of the places but more of the tubs are getting restored now....

Too much barn...not enough time.

Use an old technique from the carpenters...an "angle finder"....the only problem is, your going to need to find the early 911 trailing arm layout...really easy...find someone that ownes one...explain what you're up to...take your angle finder...measure and lock and your done.