i just had my rear torsion bar changed for a 3mm thicker one, and it was suggested i do something similar to the front.
car is a 1978 SC, i was told the best solution is to put an older style sway bar in which actually has to pass through the body of the car almost like the rear torsion bar, only at the front?

The white car I posted (mid drift) wears a stock 72 911S front bar and RSR valved shocks on the front.

Perfect for a skinny tired car.

Understeers on the throttle and oversteers off throttle, just like it is supposed to ;)

You can probably get away with 3mm larger in back and the same fronts since the cars were set up a little front stiff from the factory. For autocross you usually want the car more oversteering, not so much for track. Revalve the dampers to suit the front and rear torsion bars, though.

You really should only need one anti-roll bar, adjustable, and on the end that is soft in relation to the weight distribution (when you take into account roll centers and springs).