Rob,

Don't use screws, use Al hinge material with a piece of stainless wire
inserted from the front of the cowling. Much neater and you'll never have
the "bulging" between the fasteners. Quite a bit more work to accomplish but
with a big pay-off in the end.

I used this method as did a number of other builders (seen at the Redmond
bash over the years). Besides good looks, absolutely holds the cowling
firmly together and eliminates the inevitable slip with a screwdriver (and
nasty scratch in your paint) when removing the top cowl.

Dan Schaefer