If you really take 6-8 trips highway trips think about what rpm you want to live with
before picking rear/tire size/trans combo, that adds up $$$ . If you are going to have to buy an intake might as well get an aluminum saves a lot off weight. Small cam 210-215 @ .050 read up on all the flat tappet cam/lifter failures and choose carefully, break in procedure
and oil critical. Clean up the heads,better springs, Mr. Gasket .028 head gaskets.
All other suggestions above make sense IMO.