I'm doing some winter upgrades to my 68 Plymouth Road Runner. It currently has the stock 383 CI engine with factory cast iron exhaust manifolds. I want to install some Edelbrock #5090 E-Street cylinder heads along with a throttle body injection unit. Edelbrock says that they "think" the factory exhaust manifolds are compatible with their heads. My question is, does anyone here know for sure if the factory cast iron manifolds will work? I'm just not a header guy and would really like to keep the factory high rise exhaust.