You could use your stock hood as the buck- coat it with some kind of release agent- then fiberglass over it. If you smooth it nicely when laying your glass you may not have a lot of smoothing to do when it's done.
As far as the cowl- you could use floral foam to get the shape you want on your stock hood; But you'd need to paint it or cover it with tape/aluminum foil or something, to keep it from sticking to your fiberglass (if the foam sticks, you could just tear it off of your f/g piece once it's cured).
When it's cured pop it off, flip it over and lay down some foam or wood strips and fiberglass over it to give it a little strength.
Here's a little turorial
I found on making a fiberglass hood. Maybe it'll help you out.