G valve train settings?

Tightening the lash will increase the top end power while loosening it will increase bottom end power. Be careful how far you go either way.

Jack,
Here's an idea of what can be done with changes in duration by advancing or retarding a cam thru chaning the valve lash. This torque curve graph is from changing duration by 20 degrees. The most you can hope for by changing lash setting is 4 or 5 degrees -- but the relative curves of more or less lash is the same.

This is a auto engine, the green curve is with less duration (the effect you get by increasing the clearance between rocker arm and valve top). You can see you don't get any greater torque levels, you just shift where it happens in the RPM range. So if you want it to lug --have more torque -- at 300 to 500 RPM on the G, you starting increasing the lash. You'll get more results from changing the intake side than the exhaust side. If you're at .020 on intake, I'd go to at least .022 you have on the exhaust, then see what happens at .023 and .024, etc. There's a point when you might be in danger of falling of the cam ramp, and also with too much lash there's just not enough fuel flowing in. So change in small increments - be careful. Sure helps to have a dyno when you're doing this kind of stuff.