generally Rover cams stayed pretty much the same till eighties when they were gradually tightened up. The final 4.6 cams have far less overlap and the engine has far more low down torque than previous iterations.
Unless you are revving well over 6000 rpm a 3.5 will never breath 390 cfm, chances are the secondaries will never get to open even at that size when tuned correctly.
My car currently runs its 3.5 with a little over 11 - 1 compression, full 1 1/4" headers into 2" collectors into 2.5" exhaust with two straight through silences (in name only) plus blueprinted, match ported and widened P6B heads and otherwise standard manifold and carbs. Oh and a stage two cam by Heatseeker advanced five degrees. It gave 226 lb ft at 3000 and over 200hp just over 4000 (we stopped at that speed in case something broke...) on the rolling road. Which is kinda awesome but down below 2000 it was still pretty ordinary so not too quick around town till I changed the diff to the 3.54 ratio of the 2200. the point here is that the 3.5 needs revs to work in near standard form and if your driving on the street your better off with small overlap cam. same deal with the lift. High lift is great for the high end of the range but at low speeds the gas flow slows down to much creating mixture, gas inertia and distribution issues.
A standard 8.13 - 1 engine can be tuned quite nicely for road use if run on low octane petrol with lots of advance. they feel gutless because they are seldom tuned for power and they use the same cam (and gearing) as the 10.5 - 1 engines which have to much overlap for them.
