E/T's with MP 312 mech cam S/B

I have used the 590 cam in several engines. It's a good grind but you could probably do better. However if you already have it, go for it.

I've been 10.80 with that cam in a 360 with W5's.

What you need to consider though is valve lash and some pushrod flex to get your net valve lift, what you want to achieve is max lift at max flow and hold the valve open there as long as possible.

So your .590 lift cam is actually going to net out at about .570 which is .030 below your peak head flow. You're leaving some horsepower on the table that way.