Agreed though I think the values will reflect what has happened in the early 911 world. Original will achieve top tier values; but a proper build with a spicy engine and gearbox upgrade will also achieve nearly as high of values.
I agree with Steve and Mike. If you have a matching number motor, do not get rid of it whatever you do. Just store the original numbers matching motor, then do what you want to your car. If that is what you have. But I have said this many times, I think in the not too distant future, maybe a couple years even, the more original, the more valuable (Not the
same as Hagerty suggests). Anyone can make a hot rod (and I'm not taking anything away from people that do that, there are beautiful ones out there, most of your cars have beautiful 3.5L motors, injection instead of carbs etc). But one can't make original paint (no re-spray over the years), low mile, no rust (Close to no rust, let's be realistic), straight, numbers matching coupes (or E3's he he). You simply can't do it. They have to come that way and there are very few left in the world that meet that description. It's not everyone's cup of tea but that doesn't matter because logic would tell you they should be worth more then standard swaps (Not talking factory Alpina's etc), since they cannot be duplicated that way. Whether the BMW crowd will care that much, time will tell. The older they get, the more I think that will matter...... I will say this too, from somebody that is trying to preserve as much originality as possible with a couple tweaks of my own, but "bolt on off" stuff (always saving the original part); it is getting harder and harder to find someone that really knows the Zeniths (And thank you to all of you that have helped along the way; it's a team effort). I think that was the original motivation for a lot of people to go with Weber's or injection. Then the thinking was; might as well get a bigger displacement motor while your at it, especially if your motor is not matching. But even the local mechanics around SoCal will tell you that tuning the Zeniths are tricky (And not just because they want more money, I truly believe there is an art to tuning them). But once tuned right they are faster than the Dual Weber's. Maybe not triple side-drafts, but if you can keep it stock, be faster, and have the great carb sound, that is a win/win/win in my book. I finally, just yesterday had the master himself (name to be withheld for privacy) get his hands on them and man, what a difference, they are screaming now. And that M30 sound with the dual Zenith carbs, when they are humming just right, there is no better feeling or sound in the world. Other then when on straight pipe race cars. But they still sound amazing with a stock muffler. I had the biggest smile on my face yesterday, hit 100+ smoothly and easily with stock 4-speed on the drive home. I don't need anything more than that at this point. But there are only a handful of people I think in the states that have that talent. It's a dying art unfortunately (in my opinion). And if I ever lose a contact like that, then I may have to make a tough decision, and go another route. Or try over the next 20 years to learn the art of tuning Zeniths, but realistically that probably won't happen. So I understand why people go to the injection, different motor, Weber's etc, but sometimes taking the hard road can be more rewarding. Good luck in whatever direction you go, keep us posted.