85 Suburban w/5.3, leaking power steering pump

[SBTork]

Ever since I've finished my LS swap on my '85 Suburban, my new power steering pump leaks. I replaced the one that was originally on it, donor was fro an '05 Avalanche, with a new reman one. I installed a new steering gear, pump and both pressure and return lines at the time of doing the swap. It took a several hours to bleed the power steering system which to me also seemed very strange. I thought these systems were very basic and bled air out of them very easily. As far as steering feel, it feels a little tough or hard to steer and the pump is still making a light/slight whine noise at idle and when steering. Maybe it needs to be bled more or in a different way. I do not know for sure where on the power steering pump it is leaking. Maybe the cap but it seems like it's leaking from the back of it. The pressure line is good and tight and has a new o-ring on it. The o-ring is one that came with the new line for the '85, maybe the '05 pump needs a thicker or different sized o-ring? Any input or ideas?