Andrew vanman87 said

You are Comparing a engine with a better flowing head ( which the magnum has over 2.02 x heads) you could put a magnum head on a 340 and the hp numbers will jump or a cheap speed master head ( which would still outflow stock) . Apple to apple comparison would be comparing a la 360 with x heads .... In my eyes the only real value is in cost rather than performance 360 Magnums are just way cheaper and plentiful. People are not giving up their la blocks anymore ...

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• First, I bet some will argue that point about the magnum head being superior to the "X" head in stock form or if they both were even "home ported". I will say I think if the magnum head has an advantage in performance (which I think it does), it's not much.
• To your second point, the LA 360 is almost always going to have factory dished pistons (eww) and in most cases the piston being in the hole a tad more than the magnums. This will give the magnums a better compression ratio, and that's not including the closed chamber heads boosting compression as well if the LA 360 had X heads.
• Though I haven't weighed the components, there are enough folks out there stating the magnums have a lighter rotating assembly and better ring placement on the pistons.
• My opinion is the magnum would outperform the LA 360 with X heads if the same size cam, intake, and carb was used on both stock short blocks.
• Oh, I have a LA 360 with the cheap speedmaster heads in one of my Dusters.