310 is relatively easy with a W2 head and "the pinch" isn't an issue with that head. Core castings and cracks on some of the econo heads are a problem and knowing what I know now if i used the same casting I would NEVER use the recommended torque values and would do a couple of other things differently. Part numbers get very confusing when dealing with that head. My econo heads both cracked right were the W2 is cast on the header side deck surface. Stock those heads maxed out at 260cfm at between .450-.500 lift and then fell on their face. Bowl and short-turn work easily gets them 300+ even with the 2.02 valve. Then it gets a little trickier and time to upgrade valves.