Cooling question

Hey, I've got a question about my cooling system. I'm not necessarily worried about the temp it runs at, however I don't understand why it's running a bit hot.

Here's the deal.

1970 Dart
340, 727, 3.23SG
10.5:1 pistons
Comp Cams 280/480 (????) .. Can't remember specs..
Edelbrock air gap
Holley Street Avenger 670
3000 stall
36 degrees advanced, 8 initial

Champion Aluminum rad, 22" 3 core
180 degree thermostat (tested it in a pot of water, it opened when temp reached 185)
New water pump
New hoses (bottom hose is not collapsing)
Shroud
Tranny cooler
7 blade fan, 3/4" away from rad, far into the shroud

My question is, why is it running steady at 190, then idling at a stop light it will rise to 198 - 200? Without the shroud it'll rise to 210 sometimes.

My cousin runs a 9.5:1 340 with a stock 22" rad, and a 4 blade fan, no shroud, at 180 all day long.

Thoughts??