can a stock FPR handle a 255 pump...
Yep, it just dumps all the excess back in the tank.
I've heard from many sources that the stock regulator diaphram will allow extra fuel to pass by at idle and fuel pressure will actually creep up. Why do you want/need a 255?
On a side note, my Kirban adjustable just took a shiznit. I have to pick up a new one tomorrow. I run a 255 Wabro with 24 pound injectors set to 48 PSI without vacuum.
The factory fuel pump died, and I didn't wanna pull the gas tank again when I build the H/C/I motor for it eventually.
I've been running a 255 walbro on the stock fpr for about 2 years now with no problems. I say go for it