Mine were side feed sards:)
Killer T has these injectors fitted, not sure if he fitted them himself? Might be worth a pm if he is still about.
New o-rings should only cost a couple of dollars each, and you should be able to source them from any fuel injection shop, or rotary shop. Would be a good idea to do this as matter of course, as if one goes on you life could get pretty messy, especially whilst boosting:p
I would hope they are pretty tight or they wont seal. I used engine oil to lube my sards up, and they were a pretty tight fit. Perhaps you need a slightly bigger holes in the fuel rail? Any engineering company should be able to help you out there, or a decent performance shop - hills would definately be able to help.