Hi Dean,
As others have indicated, this may not be the root cause of your problems. Because the mechanical fuel pump is mounted directly to the back of the engine, what may be more important is making sure the oil cooling is adequate, because the oil temp will effectively be what this pump body temp is. If the pump is too warm, as the fuel is drawn under suction to it, it may boil and mean that the pump is only drawing vapor. To help this situation, use light colours when painting your tanks to limit solar heating, insulate the fuel lines as they enter the engine compartment, put a titanium belly skin with ceramic insulation beneath the forward floor and ensure you have the best possible airflow through your oil cooler (good baffles, gaps sealed with RTV etc) or increase the cooler size if necessary (many -7 builders raise the cooler by a inch or so to improve airflow).
Tom
RV-7