I used a Fel-pro extra clearance valve cover gasket set on the advice of the FRPP help desk. I'm using your exact set-up and it works great with stock valve covers. If you want the part number for the gasket set I can dig it up for you.
Since its 1.6 rockers, which is the same as the stock, you'd think that there would be clearance. I put hearty 1.6 Comp Cam steel rockers on my 92 GT-40 aluminum heads, and had no problem due to the way the inside of the valve cover was manufactured. I think it was 1990 and newer year's stock valve covers that will pose little problem for clearance of 1.6's. Put'em on and turn the crank by hand and listen real close.
ratio wont really affect the clearence. in my 1st post, i had frpp 1.7s and they fit perfect. and my friend had some off brand 1.6s and he had to grind the inside of the covers. its all in the rocker's soze and design.