Flathead fuel pump question

I've got a '50 shoebox w/ FH V-8, I've heard of single action fuel pumps and duel actions fuel pumps. What type is the best choice and why.

 

single action is just a fuel pump,double actoin is a fuel and vacuum pump in one,it will suplie vacuum to your wipers at al times

 

the duble action pump is for vaccuum wipers

 

I bought one for my 56 chevy inline 6, and it didnt seem to help the wipers a bit, they still stall under accelleration.

 

i had one one my 61 falcon,it worked great

 

vacuum sucks.