Back in the 50s, my dad made a split manifold for his 216 in his 51 belair(yeah, i wish he still had it, too). That was the downfall of the engine. The factory line burnt in two and run the engine out of oil(i still have the engine!). He said that the lines were not touching the manifold, but the new downpipe he installed created enough heat too close to the line. Good luck.
