Just went through this myself. Have a G-62 on a 29# Sea Fury that was running fine but came back covered in oil from the carb blow-by. Put a stack on it to help the problem and was rewarded by 400 less RPM on the same prop and fuel. 400 RPM on a 22-10 prop makes a big difference.
I leaned the needle a 1/16 of a turn and got back about 200RPM , so I screwed her in another 1/16th and got back to my old groumd RPM. Will fly this week end and let you know how the performance is in the air. This plane was clocked by radar at 95mph on a flat level pass so we'll see how she does.
By the way, the oil blow-by problem went away on the ground. This engine has the short riser block between the carb and cylinder which produces more fuel blow back than the stock version. The blow back is a combination of vacuum at the the entrance to the carb due to passing air and the intake timming of the G-62. Any engine with sub-piston induction will by nature blow some of the fresh incoming charge back into the carb. My situation was made worse due to the short riser block used to keep the carb from being right up against the cowl.

Lou