Hi Steve,
Glad you fixed it! Something I didn't think of before was that a failed fan clutch could replicate symptoms of a bad radiator. Here's how: If the clutch is OK but just never engages (to spin faster than ~1500), it would cool OK at idle but not under load and/or when really hot. BUT, if the clutch was totally shot, and wasn't even matching RPM's up to 1500 then it would barely pull any air at all, even at idle. It would be kind of freewheeling all the time. That would cause hotter operation at idle. I wasn't sure if the clutch could or would fail like that, but I suppose it's possible, and your experience somewhat confirms it. But anyway, if it won't exceed 100C under most conditions with warm ambients, I'd say you are all set! Congrats!
Best regards,