Junkyard 5.9L Magnum + Edelbrock LA heads build

Squeeze is squeeze. The thermo efficiency of the aluminum will not be a draw back. At your altitude, A 9.0-1 ratio is good for 87 octane. If the cam is large-ish, it will just feel a little soft on the bottom end.

Cool, yeah I'm not too concerned about the heat transfer with the aluminum heads, seems like that's finally been generally accepted as an old wives' tale. Maybe at very low RPM there might be a small difference but each cycle happens so quickly there's barely enough time for the heat to transfer from the combustion gases into the head before it gets exhausted and a fresh mixture is pulled in.

Cam is 222/226* duration at .050" (274/278* advertised at .008" lift) with 110* LSA and 106* ICL with .548/.544" lift with 1.5 ratio rockers.

Honestly after blowing up my last engine due to constant pinging from too high cylinder pressure (much too small a cam for 10.5:1 SCR) it'll be relieving to not have to worry about that. Just fill 'er up and go!