906 or 915 ?

DO the 915s come with flow numbers? The 906s if redone and ported will be the devil you know, versus the devil you don't know.
I asked him if he knew that number, but he did not. He said he just pulled them off his 383 bracket duster racer that was running 10.70’s. He is going aluminum… they are 3 hrs away so I have to figure another 150 in fuel,, he had them listed for 1200 almost 2 weeks ago,,down to 1k now,,, money is always tight on my end, so I was gonna offer 750 and I pick up,,,I assume I will have that in my 906’s for hardened seats, a good valve job and ports matched…. They are probably worth 150,, 1969 casting numbers( they been cleaned, mag crack checked,, new brass freeze plugs..I am leaning on staying with my 906’s,, my 1969 block will get deck, squared, bored and line bored, balanced rotating assembly… I just want a powerful , reliable,, stock looking engine… in a original m code dart.