Did I screw up Edy's>R/T's

Are the R/T's open or closed chamber heads? That makes a big difference. Closed chambered heads will tolerate more compression. 10.2 is pretty high for open chambered heads but do-able with closed chambers. Like Sterling said the cam affects things too. A long duration cam will bleed off cyl pressure making the engine seem like a lower compression engine. That's why you need high compression for large cams.

One member here runs stock magnum heads on a 360 with 10.6-1 compression and only a 268 cam and says it runs fine on 89 octane.

BTW: My 360 is 9.9-1 compression and I'm running open chambered X heads but I do have a fairly large cam for the street. Runs just fine on 91 octane with 34 degrees of timing. I even took the timing up to 36 degrees once but it didn't run any better so I backed it back to 34 degrees. Even at 36 degrees it didn't spark knock.