AutoX,

For an A body with at least 3.91-4.30 gears with a 3200-3400 stall 9.5" vert and a HR cam in the 232-236 @.050 range on a 110 split in no later than 106. Performer RPM or AG intake is your best bet and a tweaked downleg 650-700dp. A 10.5:1 340 with at least 255 cfm of intake port will get you right at 400 hp in a very streetable low 6000 power range. That's plenty of airflow potential for that 400 hp range.

Bullet lobe HR12 is 234@.050 and 155@.200 and .565 lift with a 1.6 rocker, I'd look at that one really close in a single pattern for what you want. Bullet HR's work really nice and rev QUICK.

Heads are really key, the old iron can be pretty darn good if you know where to whittle.