Imo, the valve lift is a non-issue.
Op says he’s at the mercy of the cam grinder?
They’ll sell you anything you want.
And..... Imo #2(and we all have ‘em), a 272/280 cam in a 410 and 5300 stall is a mismatch(I ran 5400 stall in a 383 with a much smaller flat tappet cam and a dual plane manifold).
It’s self evident by the cars performance that the combo isn’t optimized.