I like braces that run from the firewall down to the upper A arm mounting points. Hotchkis makes these:
http://www.hotchkis.net/product/1967...k=&yr=&md=&sm=
They are a bit more complex and heavier than I prefer.
Pro-Touring F body makes these for second gen Camaros but not first gen's.
http://www.pro-touringf-body.com/cha...omponents.html
They are lighter and simpler but won't fit a first gen F body. Herb Adams invented this style and they stiffen the front sub by 1/3rd.
You could have some made up. The firewall on a first gen needs a doubler plate inside to spread the load and resist cracking if these are used.
I also tested a 69 camaro with full roll cage. The front braces went to the subframe kickup about 10" behind the upper A arm mounts. I was surprised it didn't stiffen the front sub torsionally any measurable amount.
I haven't tested the Chassisworks type underfloor braces. I'm sure they do good things, but ground clearance is usually so tight, I'd be worried about clearance. They won't help the area ahead of the firewall at all.