To the OP...this is stuff you should ignore, as I said earlier. A stock, unported W-2 will support 450 HP at 6000 RPM on a milquetoast 340, without a sweat.
Don't fall for the old line that W-2 stuff is race only. One would think that the motorsports world would have evolved passed this.
I will say it again. The heads you have are fine for what you want. Especially if you don't have a bunch of parts already. Valves, springs and all that crap all cost the same. The ONLY issue is rocker arm cost. Check the web. W-2 stuff comes up all the time for a fair price.
Don't get suckered out of using these heads.........please don't.