other mfr fuel pump

My fuel pump appears to be dying. The stock part is over $300. Has anybody put in an aftermarket pump on a stock Malibu? I think the smaller Walbro (190 liter/hr) is still way over the fuel requirement for the 2000 3.1, so I'm not sure I can do it without also changing the fuel pressure regulator and checking the line size back into the tank. Just wondering if anybody has already been through this excercise.