That Corvette manifold is one of the better ways to run dual exhausts, since it has a pretty conventional heat riser box and flap valve which will bolt up to a standard 1-carb intake manifold without all the exhaust heat problems the Fentons and other split exhausts have. However, the prices those original dual pipe manifolds bring these days is just short of legalized robbery. I think they could be bought over the counter at a Chevy parts department for less than $50.00 back in the 1950's!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!