blocking air flow too much?

I went for a drive tonight after getting the exhaust hooked up and the tranny filled and the cooling system flushed.....
I installed 2 10" fans, rated at 1500 cfm each, and built a shroud for them to serve a few functions: a mounting place for the fan relays/fuses, a mount for the fans themselves, and to allow the fans to pull air through the whole radiator, not just where the fans are mounted.....
it acts like maybe i don't have enough air flow while cruising though.....the temp creeps up slowly....it took about 5 miles at 45 mph to get to 225-230...by then i was back home and shut it off
anyway....the shroud is aluminum and covers the entire radiator except the fan area....2 10" circles are cut out for the fans....and then the sides are 3/4" tall....so it's a big 3/4" deep box basically....am i blocking too much airflow at cruising speed? i kinda thought maybe i needed to make some holes in the areas of the relays and the fuse holders to allow more airflow at speed....

sound like it's sufficient for idling in the driveway (it never got above 200), but with throttle it needs more open area?

it didn't do this before, when it had a nylon flex-fan and no shroud...it just got hot idling....