Decent piston Crane R280 cam Ported 452/906 heads M1 w/adapter and a 1050 Compression 14:1 + Good machine work and a little attention to details Keep the timing in check and live with the minimal cap walk.
Hardly 12k, more like 3k (assuming you have a carb and can do some work yourself), and will exceed your ET expectations. More perf should be expected with a set of heads, but not necessary.