Hi ahicks
At this point I don't have a clue on the that, as my G-62's have custom style pitts mufflers, and the RCGF-62 has a home made pitts style muffler and I have never put them on a scale.
But you sure could be right, from the looks I would guess the heads came out of the same casting mold, but that is ware the similarity ends. I have never had the G-62's apart, they have side carb's and the RCGF-62 is a rear carb.
Top end's are vary close in RPM's with the same props, So like I said it's not a big deal, as we both like our engines.
cheers bob T