Fuel Return
If I understand your question correctly, you need a fuel log for the return regulator to screw in the back side (return side) of the fuel log.
Check the Summit catalog for your applications. BG - BLP - MOROSO - HOLLEY, etc. all have fuel logs to attach your return regulator.
Use -8 fuel line for the return. You will need a fuel gauge (Autometer is the most accurate) to determine your positive line pressure and adjust the fuel return regulator for recommended pressures.
If you have questions, give Bo Laws or Barry Grant or Holley a call. Their tech service will work you through the details.
Please note that the return regulator is different than the common fuel regulator and that alcohol applications are different than racing fuel regulators in their materials - so be careful to get the right thing. By the way, I prefer the pill or check ball regulator to the dampener type regulators - you might want to research some carburetor websites for more information before you make the final purchase decision.
Good Luck