The factory LRE 360 had a 340 speed camshaft from factory and worked very well, when I first rebuilt the engine years ago I added the Aluminum LD340 intake, headers and used the mopar performance 268* .450 .455 camshaft and was happy with its performance (like Jpar first I tried the MP .508 cuz I thought bigger was better - it was lopey but that was it...)
