Really the only thing that's different between the 210 horse 327 and the higher horse versions are the cam & heads. Early 68 is when they went from small journal cranks to the large ones but,for the power your looking for the small journal should work nicely. Goin with the new grind cams would definately be the way to go. And I gotta aggree with vinniekq2,you can find a 4sp auto it would really help wake it up. Painless has a control module set up for vurtually every 4 sp auto Chevy has. If you find a 200r thats even better cause it doesn't need a module. Remeber that the 210 hp rating was a gross number,not the way hp is rated since 72. Even a set of Iron vortec heads flow better than any head that came out of the 60's and you can pick them up rebuilt for dirt cheap. Then it's just a case of getting the right intake to bolt on to it.
Foot to the floor,hair back,knuckles white!