This is kind of a goofy question, but is the distance between the fuel inlets on a Demon the same as a Holley 4150?

Also, I'm constructing a new fuel system. It will consist of a 1/2" line from tank to Carter 172GPH pump (including the sending unit), then a -8AN from the fuel pump to the carburetor fuel log. Now here's my other question: Should I run a -6 to each carburetor inlet from the fuel log, or -8? I would think a -6 would be plenty since there are two carb inlets, but I wanted to be sure.

-6 would be plenty IMO. I think my carb feed line to the rear bowl uses -4, and I am only running -6 from the pump to the carb.

Overkill is generally a good thing with fuel systems, so I am not saying go to -4 . . .

Thanks.

I am not sure I understand what you have here.
With a fuel log i assume you are running a single carb? How are you getting a duel inlets out of a single log? What kind of fuel log do you have? What are you running for a carb?
If by chance you are running a 4150 style carb with log then aeroquip has a fitting that connects the log directly to the float bowl. Part #FCM2193 is a -6 fitting and #FCM2192 is a -8 fitting. Personally i would use a single inlet and the -8 fittings.

Missed part of your post. I believe the race and mighty demons are a 4150 style carb. King demon is dominator style.