For what I understand, it doesn't really matter. In fact, if you're getting a new pump, it's best to go with a 255lph one to support future mods down the road.
Because even though the 255lph has the capacity to flow more than the 190lph one, that doesn't mean it will eat up more gas. Just that if your engine needs more fuel, the 255lph can provide a larger amount than the 190lph one.
If that makes sense...
No, no, I HAVE the pump from my old car. Its still good, so Im just gonna reuse it, but I need a the gaskets and junk. Comprende?
That
should work...

Thats what I hear from ther people. I guess Ill just order it and see what happens, hopefully it fits.