maybe some early Mitsu pump from higher power car could swap in. but if buying new I'd go for a Walbro 255 lt/hr, never have to worry about starving.
i talked to a vendor, they're mostly same pumps with seperate install kits with hose section & electrical connectors. hardest part was finding a pre-filter that fit the bigger pump & had the matching angle of the stocker so it sat right against the floor of the tank.
i had to put my project on hold at that point so don't have any definative answer. :depressed:
I'd try the your local Walbro dealer for starters, maybe RPW?.