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I actually have the sr's now, they flow 340 or so.

Like people are pointing out, it depends.
On the flow benches I am familiar with, an SR flowing 340 cfm will be a max wedge port. If not, the number can't be compared to what I know.

A fully ported, max wedge, Victor head can flow ~370 cfm. So if the engine is built right, it could support about 70 more HP. But out of the box, standard port, the Victor will flow less than your heads.