First, maybe you can tell us if you're using the DD nylon bolts, then try replacing them with metal ones, because the nylon can'y give you much clamping pressure.
Second, you could tell us your water temp (dip a thermometer in your loop) and report here. (We'll analyze it for ya
)
Third, your rad should be ok, but the fan is really critical here, especially since you're running two pelts. Actually, the BIX is really on the edge of the heatload that you're putting to it, maybe you'd consider a big, fat heatercore? (Give me a size, and I'll give you car models). It's not just a simple matter of max heatload, it's also about how you can keep your coolant temp as close to ambient as possible (in a "no pelt" rig).
For more info, you can check out BillAdams's radiator roundup article on OC (but the graphs have been revised since then).