proper break in on a rebuild?
 

i'm soon to be purchasing a TII with a newly rebuilt engine, the owner has driven 1k miles so far on it, and hasn't taken it past 3.5. I was told after 2k your ok to start driving more agressive, but i was wondering what would be the be the best way to properly break it? I'll be driving it back across a state or two also, so i'm weary about highway driving.