If you are talking sway bars, I will use SCCA rules here for stock class. If there was not a hole in the body and matching factory pieces adding one is against the rules.
I would highly recommend adding a front sway bar, stabilizer, anti-Roll bar, fulcrum, what ever you want to call it.
If your looking to go stock and you do not have the stuff. post a WTB for front unit roll bar in the classifieds. It will have the bar, bushing, cups to hold said bar and business in-place, maybe the bolts. Two arms, provides fulcrums so the thing works. Two drop links. hopefully bolts and new bushings.
Most likely have to add. Tabs for the arms, to look stock they ned to be spot welded on.
Should add, a Brad Mayer 914LTD front sway bar mount kit. you do not have to cut into the tunnel below the gas tank to mount it up. It cane be epoxied in place I prefer to
them in place. But then since you don't know me you don't know I prefer to weld almost everything in place.
Referenced here is you will need to pull the gas tank, unless you are a mutant, or you have a highly trained population of snakes, that have laser beam welders built into their eyes.
I have thought of an elaborate way of doing it with out pulling the tank, requires borescopes, small tools, and special tips on your spot welder, but it can be done. Not one to say things can't be done, it is way more cost effective to pull the tank. Which requires the front trunk lid to be pulled.
Which then leads down a slippery slope, of jacks stands years of your life dedicated to getting the car back on the road.
To avoid that you could find a 911 SC with stock sway bars and swap out the front suspension minus the struts and brakes, and wheels, and it will look almost stock.
If for some odd reason we are talking front facia, spoiler, aerodynamics. Stock was a piece of metal that finished out the front of the car, gently rolled under the noise. Many popular options beyond that, but that was what is stock.
In both cases it is very easy to go from stock, too wild. One of my 914s has a roll bar supported with roller bearings it is a 1" 3/8" big, and used stuff I sourced off the NASCAR circuit. It has been highly modified see the welder part above, and well had its purpose.
I am also building a rest-mod in honor of my father, which has a very old school period correct sway bar, made by H&H runs on a set of delrin bushings. Two different cars to different goals.