They're decent heads, in the right application. The chambers are way, way smaller than your open-chamber heads and with your shiny new flat-top pistons, it's going to give your CR a massive bump. Your stock CR was ~8.5:1 with the 8cc piston dish and 78cc chambers. Going to a flat-top piston took that to ~9.2:1, which is a pretty reasonable CR. Swapping those 78cc heads for a set of 58cc Aussie heads is going to take you straight to ~11.6:1 compression. Great, if you want to run race gas in that thing 100% of the time, no so great in reality.