Radiator to pump inlet?

I don't have my pump (a Mag 3) yet for sizing (it's in the mail), but here's what it looks like so far:

My rad was a large heater core from a late 90s Gran Prix which I cut in half and is now a single pass radiator, approximately 10"x4", which fits nicely in the bottom of my case and gives the approx surface area of the Chevette. As an added bonus, it's a single pass (outlet at each end), so it should cool the water fairly well. The only thing that concerns me is that I'll have to go from the rad to the pump inlet and then from the pump out to the cpu block (it's a tight fit, as the rad's fairly long with the fittings). I realize the optimum is pump->rad->block but the consensus is that it makes a very small difference in cooling. However, do you think the pump will receive enough water from the radiator? I can't just reverse the flow as I have few options for pump orientation. Theoretically, it shouldn't matter if it's a closed system...what do you think?

I doubt it'll make a difference either way. One bonus of that, in fact, might be using a larger size of tubing (5/8" or 3/4") from the radiator to the pump's inlet.
That would increase flow.