I'm not really too familiar with any of the post '80 302's but aren't the rocker assemblies 'bolt down' style rockers? Personally I really like the older stud mount rockers better. And i do believe the studs on that head are 3/8" studs unlike the post '73 302 heads which are 5/16" with a torque down style rocker nut.
My heads CC's out to be 54.5 (I have '66 4V castings) and had them ported out and added 1.94/1.60 valves. All costed about $550, but this was in 1996 and very few aftermarket heads were really affordable then.

The BEST route would be to just go with aftermarket heads if you want to get really serious. When on a tight budget the '66 castings, with a few mods, would be just fine. Though I'd still research aftermarket units as prices have been declining.

Your typical cast piston nowadays will sit about .023 (give or take .005) below the deck (of a 289 or 302 up to '73) and depending on the valve reliefs (usually -8cc on a 4 relief piston) Will put you right around 8.5 to 9.3:1 on the compression scale with the 54cc heads and that includes a head gasket thickness of about .030 when compressed.
Where Ford comes up with 10.5:1 must be a pop-up piston or a different wrist pit height to make the piston sit higher in the bore. (common on FE engines)