What to do for sway bars?

[zippyfiat]

Hi all.  I am building an 850TC nurburgring replica (circa 1962).  I want to upgrade the suspension to make it safer so that I minimize the chance of a roll-over due to the rear trailing arms tucking in too far, and flipping the car.  I am not sure what these Abarth versions had back then.

Can I adapt sway bars from a Fiat 850?  Is there another option?  Sway bars would improve handling anyway.  What about a restraint on the trailing arms to limit movement?  I hate to deviate from originality, but safey comes first.

TIA,
Gil