found these 460 factory cam specs. Looks like my cam should outperform it.
1970 429/460 passenger car engine (incl. Thunderjet) Cam Specs:
256°/270° @ SAE
193°/206° @ .050"
.253"/.278" lobe lift (.443/.487 valve lift)
110°/116° lobe centerlines - 113 LSA
Not sure how the heads compare to the 460. Didn’t the late 60s 460 motors have around 375hp?
So, I would take Iowan's question in context of your exhaust question not just a cold performance question and answer "Likely a little more but similar to one with a set of headers and good intake/compression"
The reason is, the 460 will have more cubes, better heads, but less cam, but will still make power in a similar RPM range, especially if it's an early one. Keep in mind, the 460s have a much better head design that will equal or outflow your Edelbrocks out of the box, so it "needs" less cam
So in that light, yes, it's about like an early 460 and a 2.5 mandrel bent system will be plenty, if you were going higher RPM, a 445 or a 460 for that matter would start wanting more exhaust.
However, your pic almost looks like to the dumps it's 3 inch then 2.5 after, is that correct? If so, if/when you go to the strip, open the dumps and let her breathe