Ok I had the chance to run these two engines and I was surprised by the numbers. Both were closer than I thought. The temp was 64.7F, Humidity was 49.1, dew point was at 45.6, baro was at 29.88Hg and density altitude was at 591.
Both were run with in a 10 minute time span with same prop, same fuel, same test stand and same glow plug and same needle valve(not that it mattered). Both were ran up and I recorded the first rpm number and then a second number with some heat in the engine. Prop was an APC 14x7 and the fuel was 30% nitro and 20% oil. The DZ 70 turned 10,420 and once warm turned 10,290. The FZ80 turned 10,530 and once warmed up it turned 10,410. Both of these were on a header as I didn't have time to install the mufflers. I don't run the mufflers so not sure how much the drop the RPM if any at all.