I'd suggest you use this model of Walbro pulse fuel pump:
http://www.arcracing.com/servlet/the-65/Walbro-pulse-fuel-pump/Detail
http://www.arcracing.com/servlet/the-461/Blue-Fuel-Hose-Gas/Detail
http://www.affordablegokarts.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=A&Category_Code=PFS
But buying/installing the pump/filter/lines is the easy part... the tricky part will be installing a pulse fitting in your engine that's needed to operate your pump.
First you should read this info about about installing pulse fittings:
http://www.affordablegokarts.com/fuel-pump-setup.php
I drilled a hole in my carbs factory plastic, heat-insulator, and installed a 1/4' barbed-fitting, to slide/clamp a 1/4" hose on, that supplies the pulse-signal to my karts fuel pump:
Mine works fine like this.
More info/pics in my kart thread here:-->
http://www.diygokarts.com/vb/showthread.php?t=3664
I heard this place sells speed parts for
Subaru parts industrial engines like yours:-->
http://www.exotictoybuilder.com/index2.html
You might try emailing them and ask if you can buy a fuel pump and lines/filter from them. And then also ask if they sell any other speed parts and then just casually ask what is the best method to install a pulse fitting in your model engine. Cause I dont know anything about Subie's...