Yous hould take the time to find out what you already have.
an easy way to get an indication is to disconnect the fuel from the injector rail and run the pump for a measured length of time, 20 seconds say, into something u can accurately measure. the longer you measure the pump rate over the more accurate you will be, but an accurate measure that large will be hard to find.
convert the amount of fuel it pumped into a L per min figure. TO suport 300 rwkw you would want at least 3.5 L a min. maybe more.
to make your pump run you may need to disconnect your starter and crank the motor on the key. or just give the pump 12 volts.