Wow, that's a lot for stock exhaust manifolds. Have you tried used exhaust manifolds ? I would buy good set headers for that price. I'm not sure why the headman #68310s don't fit right your LeMans. Your LeMans with a SBC should take the same headers my 81 Malibu and 78 El Camino.
Doug
I would try them if somebody has a decent pair for sale on here and is willing to send them over to Luxembourg
As for the headmans you suggested, I googled around on several sites for reviews, and apparently, I am not the only one having fitment issues on a G-Body :/ Looks like the guys manufacturing these don't pay attention to their job about positioning, routing or even aligning the primary tubes.
He is in GERMANY!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Where is he going to get used American car parts from!!!!!!!!!!
Luxembourg, not Germany, but it makes your point even more relevant
American Cars are a very rare sight. Except for new Mustangs or a few Corvettes, you won't find much. Okay, there are a few oldtimers but they all get their parts from the US directly. Chrysler did an idiotic market-suicide here: every model has been re-branded as a Lancia. They hoped to sell more vehicles under that name, but in the end, sales dropped to almost zero as they increased the prices by an average of 15-20%. Chevrolet only sells the Corvette and rebrands Deawoo to Chevys (which nobody buys either). Ford sells the Mustangs. Okay, they are selling well, but that's because Mustangs have a reputation here in Europe since they first appeared back then
And Cadillac... Well, lets just say they are officially sold, but everybody having the cash to buy one of these (base-price + import-duties + transport) will take his money and buy Mercedes, Audi, BMW...
Left manifold:
Dorman 674-203 or ATP 101083
Right manifold:
Dorman 674-202 or ATP 101084
What you would get from OPGI or Year One would be these repackaged for probably two or three times the price. They are mid-70's small block manifolds.
Thank you very much for these infos
If nobody got good used ones to sell on here, I will try these
Could you at least read the article? It showed the engine to be down something like 5hp overall after almost complete destruction of the tube's roundness....
But don't worry, your posts/words here gave me now good hints for what to google, so thank you 
