I have a question concerning the routing for non-aero type brake levers on my old Basso. I have been looking and it seems many have the housing in front of the bars with the rear tucking under and to the top tube, others I see make a nice loop/arc over the top then to their respective calipers... which way is correct or preferred?

With Campagnolo brakes front on left lever comes over stem and behind bars. Rear comes over that behind bars on right and to toptube. At least thats the way I've always done it.

The rear brake cable going over the handlebar gives a more gentle arc to the cable...the brake feels a little smoother.
As far as the f&r cables crossing/not crossing,not crossing was often called the "italian way". Crossing them,though,keeps them more away from your hands...less chance of snagging your hand in a cable loop....

The rear cable always seems to depend on stem length in my experience. Some of mine are over the bars, but most are under.,,,,BD

See Sheldon Brown on "Cables." He sez that routing behind the bar is de rigeur, but that in the case of short stem extension, in front may make for smoother transitions. His rule is "both should do the same."