header/heat riser/choke

hey guys, im new to the whole mopar slant 6 scene. i just bought my 65 valiant a week ago, and always heard some sort of exhaust leak, today i found the giant crack splitting the manifold into 2. anyways, im a fabricator, and have built headers for volkswagens, so i figured id make a set of headers for this thing. and i also want to switch to the factory double barrel intake manifold. my question is how important is the heat riser/choke piece from the exhaust manifold? im in Orange County / California. i suppose i could fab up a header that can support the choke/ and heat riser deal. this is just a daily driver for the old ball and chain. but we all know how much more efficient and fun this stuff can make.