I'm pretty sure that Porsche still sells the clear plastic ones in the pic in Tom's post #18 above, since they're also used on 911/912/930's which they tend to support better than 914-only parts.
If so, then your local dealer can get them, & PCA members should get a discount there - as well as GPR, Eklers/Automotion/PP, Stoddars, TC's Garage, Sierra Madre Collection, etc. who resell the genuine Porsche parts can also get them & may be able to offer a better price.
70-73 914s originally came with white plastic, then 74 or 75 switched to black plastic.
Plastic rivets were originally specified because you can cut them off with a razor blade to do the rockers inspection & clean-out on 914s & 911/912/930's, & were relatively inexpensive to to replace on reinstall, although many P+A dealers still used metal rivets!
Metal rivets need to be drilled out to remove, which is a royal PITA.
SS or any screws can back out, but are an expedient alternative. I've used SS screws for the belly pans' access panels on our vintage `60 Avion Travel Trailer (similar to Airstream), & they are constantly backing out with the road vibrations.
So I'd suggest a tiny dab of blue Locktite on each screw on the rockers too, even if there is far less vibration there.
Other brands of plastic or nylon rivets would work too, if they're the right size & type, as in the link at Dave's post #4 - & he's know having done that beautiful -6 resto & many others.
Tom
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