Good morning Don!
Those MTP manifolds are nice in the sense I think you have more room for air filters. Long story, but my dad bought a weber setup in the 70’s, and we lost the intake maniold some how. I found this one from Frank, but really wanted to find one that wasn’t polished and more original looking. I finally found an original, and figure I can’t use both of them, lol.
It’s always hard to price old performance parts. They are worth a lot to a select few, but not worth much to a lot of people. I probably value them on the high side because I am an enthusiast. From what I have seen, I feel like ATP intakes usually bring in $250-400 depending on their condition, and exhaust manifolds I would think would be valued around $200-300? Complete turbo/supercharger setups go for around $1500, right? I see a turbo charger header sold on ebay for a cb750 for $237.50 on august 28th this year that wasn’t in bad shape.
I tend to hold on to more then I sell anymore because it is so hard to find these parts if you really want something anymore. Good luck with your sale Don!