So, I just bought a 543...

33IMP said

I would definately run springs that match your cam, whichever head you use. I understood it was running with the e streets, so i would assume (you know what happens when you assume, right?) that it had springs that match the roller.
On the other hand, i,too, would look at the bearings, and determine exactly what the compression ratio is.

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That is correct. The springs in the E-Street are for the roller and I would indeed be swapping those to the RPM heads. I disassembled the engine (the short block is intact yet) and visually looked things over last Friday and things look well so far. With the pistons in the hole where they are and 84cc heads, the compression ratio should be approximately 11:1 according to the 440source chart on their website.