You might wish to consider cam timing if you wish to make gains in the upper echelon of the rev range.
For comparison, my 2ltr will pull from barely rolling 3rd gear happily, that is in a 109 with 7.50 tyres. I can comfortably pull OD top on the motorway but longer hills do force me to change down. Nice bit is that there is no horrid diesel rattle and I can hold a conversation! 28mpg on a steady run as well.
I've got a single SU, four branch manifold, rebuilt distributor, high compression pistons and a nice new cam.