The easiest and cheapest fuel pump will be the cube typ, made by Facet and sold under myriad differeing brand names .
The pressure is critical ! do not exceed 4 PSI, your F.L.A.P.S. will be out of stock of the low pressure (2 ~ 4 PSI) one and insist that the slightly higher pressure one is better, so on and so forth, IT ISN'T and will cause you all manner of grief, a pressure regulator is a bad thing and must never be used .
Where the pump is mounted is important too, place it as close to the fuel tank's outlet and NO filter before the pump ~ only have the fuel filter as close to the carby as you can get it .