Harry, I admire the way you are going about the restoration of your iconic Porsche, and thanks for sharing in such detail.
I can empathise with your frustration in terms of the variability of replacement parts, having had a little involvement with sourcing and fitting parts on a wide variety of equipment over a few decades.
I can remember the Porsche adverts in classic car press showing an x-ray image of an alloy wheel that was seemingly identical in outward appearance to O.E. but had seemingly obvious and potentially dangerous casting flaws.
I also remember the early days of knock-off parts in dodgy packaging trying to imitate O.E. kit, thinking back to a replacement wing for a Datsun on which the label was spelt Dotsun... Easy to spot for sure, but as time went on the fakers got better at it, there are plenty of examples to choose from right up to the minute..from medicines to aircraft parts..with varying degrees of risk in their usage..?
Obviously motor manufacturers have ever outsourced aspects of the parts they required to construct their machines, Henry Ford was expert in that area re his Model T, (-: For me the real confusion crept in when the original motor manufacturers and their original suppliers, themselves started off shoring, which seemed to evolve at a time when cost cutting seemed to be increasingly prioritised over product quality improvements..? I first noticed a drop in quality of Lucas electrical parts bought from Lucas agents and in Lucas packaging in the seventies, from then on it seemed to keep on going downhill for Lucas..
In more recent times I also think I read somewhere perhaps a year or two back that Porsche had production issues relative to shortages of wiring harnesses seemingly manufactured in Ukraine, not that I am suggesting there were quality issues in any way..more likely just one of the downsides of globalisation perhaps..
For sure some degree of confusion will ever exist in the mind, when one can buy a sparkplug from Bosch of the correct specification for a specific Porsche model, and that the imagined identical spark plug when bought from Porsche comes with seemingly nothing different than an extra form of I.D. applied by Bosch for Porsche, to enable the part to be identified as being purchased through the Porsche network....?
For sure I think I understand the motivation behind all that smoke and mirrors, more so when it comes to the difference it might seem likely to make in an extended warranty claim requiring a replacement engine/box or perhaps worse relating to a brake failure, where the Porsche O.E. I.D. may not be on discs, pads or any other item in the braking system that may not have failed it`s self...BUT..?
It matters not... until it matters... at which time it REALLY matters...? Also at such time whatever savings might have been made in running, repair or restoration using non-O.E. might be reassessed..?
Seems to me that dependant on personal priorities, if one can afford by whichever means to buy O.E. then that may be the safest bet...for many that just may not be available, but that is life..shrug.
There seem no doubt that there can be found Parts for Porsche that seem to exceed O.E. Porsche quality, and by some margin, which seems likely to be obvious in terms of Porsches manufacturing priorities and any fluctuations thereof..?
My personal Porsche part frustration relative to my 991 is more directed towards corroding exhaust fixings and others, where it on the surface appears that for not a lot more cost, Porsche could have utilised higher grade materials to not only improve the looks but the long term serviceability of the vehicles...? I guess those who have had to deal with seized bolts in suspension components would have their own ideas of improved material choices, even down to something as inexpensive as a smear of anti-seize compound when first assembled..?
Having typed that and having come across imagined improvements in equipment other than Porsche that at best created an issue not contemplated when originally fitted, and perhaps at worst caused another issue creating a domino effect, affecting of not only performance but safety... As typed a few paragraphs back, sticking to manufacturers O.E. spec kit may work out the safest option..?
As with much else it seems imagined improvements on the original can be taken to extremes in many areas, perhaps in the form of RUF, Singer and others...?
As ever, each to their own and consideration applied relative to variety being the spice of life...? (-: