Ok, looks like LS2 injectors are in the 50-lb range and they are 2.1" tall instead of the factory 2.5". I think I can swing that by fabbing brackets for the fuel rails.
Question that I never figured out... does the o-ring seal inside the bore of the fuel rail, or does it seal because the mounting presses down on the o-ring. I'm trying to determine how precise I need to be with brackets. If the o-ring seals inside the bore alone, I have a wee bit of leeway.