I am changing my mechanical belt pump with internal bypass regulator to one that needs an external Regulator. The way I had it plumbed before was the one no 8 line coming out of the pump going to a tee and then to two fuel logs that fed my 2 carbs. I now was going replace the tee with the return style regulator and just plumb a no 10 line back to fuel tank for return. My question is I see a lot of these return style regulators being installed behind the fuel log instead of in front . Would this be an issue in my application ?

I am surprised nobody answered your question.
I think the normal installation for a return style regulator is at the end of the log, (downstream from the carb feed), because the controlled pressure is in front of the regulator (upstream). In your case, (if I am understanding your description correctly), it should work fine.
I have the same line size setup, mine is -10 cell to pump, -8 from pump to reg, -10 return line to cell. I have seen a lot of people "do it wrong" and run -10 to reg, and a -8 return line, but in theory that can cause issues if pump is capable of overpowering -8 line, the smaller return becomes a restriction and can result in the regulator not being able to control the fuel pressure when the bowls are full and carb inlet needle/seat is closed, (such as when you let off throttle at stripe, or even at idle). Which can potentially push fuel past the closed N/S.