Help me put "587" heads on a 318

Those heads will lower compression a little, but I would not mill them to get the compression up.... You will get increased performance with the better flow/larger ports...

If you want to keep compression up, then I would recommend using a 66 or 67 273/318 head with closed chambers to increase the compression a bit... I am doing this right now on a 72 318... With 360 heads, it is at 7.6 compression, and with the -920 heads and .040" head gasket brings us up to 8.6 compression... I had 360 valves installed (1.88" intake and 1.60" exhaust) and the heads ported...

Or if you want to get the compression up with the 360 head, install a set of 10.5 compression 318 pistons with a 360 head and a .065" fel pro gasket will give you 9.2 compression...