Project560- first of all, let me welcome you to the wonderful world of Porsche ownership. I've been a member of this fun group for over 48 years and still have my first Porsche, a 1963 356B Super coupe.
But, let's get on to your post about FI clips. I have no direct experience but looking at your pics the thought occurs to me that you could take two of the newer type clips, a piece of scrap sheet metal, and a MIG welder and create a homemade version of the clip you need. I'd cut it to the right width, fashion into a "U" shape to form all three sides of the desired clip. Clamp it to the pair of factory clips with a needle nose ViseGrip using a Vernier caliper to confirm the size is correct before tacking it together. Once tacked, you can move the ViseGrip out of the way so you don't damage it's jaws with weld metal.
It's amazing what can be done with a MIG welder. Even a hack welder like myself could do this job. With a grinder, you can even make it look decent ;-) And, of course if you don't have a MIG, most car guys know somebody who does. Prices have tumbled in recent years. I paid $1200 for my Miller MM-35 in 1978 and still love the darn thing. It's paid for itself time and again.
Nowadays HF offers several cheapies for well under two hundred.