Ford Transit drag link on Cortina upright?

"BIGGER CAR" erm, the transit is a 2 ton van when empty, I would imagine it would me man enough, right?

I've seen it used on Cobra replicas, but I would be a bit wary to use it on a car as heavy a Cortina.

I haven't seen anything that can be used as an alternative at the top. Bottom ball joints are in general Austin Maxi, but apparently Fiat and Saab lower ball joints have been used too.

Maybe there is a beefy rose joint that you can use?

It does a little more than keep the wheel upright in that the full force of the braking torque is passed through it and the cornering loads are shared top and bottom dependent on the axial loads and direction though the axle.
The Transit link is more than up for the task on a Cortina, it will be the fabrication of the arms that will be the weak link.

I wouldn't use them, seen several snap at the threads in kit car and hot rod applications. Austin Princess fit I believe but you need to ensure they're shimmed up correctly.