Simple overheating diagnosis

[transit360]

I'm working on an RTS (taking a break from my 2 Bluebirds),
however my question is general and not specific to just one bus.
How can I tell if I'm getting proper flow of coolant through
the radiator? I will be purchasing an infrared non-contact temp gun
(where is the best place to get them?), but for now, I am collecting
advice on radiator dynamics.
I got the old bus to operating temp, but while driving I
notice she gets little hot. I checked the radiator when I got home
and on the outside I put my hand on it and was NOT hot to the touch.
The tanks on either side were super-hot. I shut the bus off and felt
the inside (towards the engine), and the top of the radiator was
warm, not hot, and the bottom was hotter. What does this tell me?
I did find on hot spot on the lower part of the radiator, and
after looking contributed it to being clogged with oil and dirt. The
rest of the fins looked good. What's the best way to clean the fins
in the radiator?
My fan is working great, coolant is good. Any suggestions on
diagnosing a worn water pump? Just looking to get this thing running
as cool as possible. Thanks.

Steve
'79 GMC RTS and 2 '98 Bluebird QBRE's