If you can squeal front tires with the brakes, they are working well enough for any ride. As was pointed out earlier, you don't actually want to lock the front tire in a panic stop as it will slide sideways and down you go. Being able to lock the front when you really, really try is just an indication that the brakes are working as well as they can.
As for the trip, consider this. The oil change interval is 1000-1500 miles. The tuneup is at 3000 mile intervals. Honda expected it to run maintenance free between those intervals. Why don't you?
Don't worry about overheating, and unless you don't have a good piston ring seal (compression test) or a blocked crankcase breather system, don't worry about crankcase pressure either. The big fins on the motor will cool the engine as long as you have forward motion and are driving in earth's atmosphere.
Lastly, if I could drive a 67 Honda 305 2 cylinder bike at 70-80 MPH for hundreds of miles at a stretch, it's very difficult to believe that Honda designed the CB350 or 400 Four with less cabability years later.
Now, the personal comfort factor is another matter. But, a resilient person in their 20s shouldn't have any more problem than a sore butt, if that.
Cheers,
