Yes.  There are 2 reasons to buy aftermarket 2nd gen frame, IMHO.  1) bling.  I appreciate that, as fine a reason as there is, no knocks here.  2) racing.  If the answer is 3) great street car, it's relatively easy to make a 2nd gen a great street car with a stock frame.
While I was at SEMA I talked to a lot of folks out there.  Engineering types and drivers.  These seem to be the favorites at this time.
http://artmorrison.com/camaro.php
Art Morrison uses vette parts, so replacement parts are out there.  I've spoken with Matt at AME and would not hesitate to use their stuff.
http://www.detroitspeed.com/productp...rame2ndgen.htm
Considered by most to be the class of the lot.  Mark Steilow uses their stuff for a reason.  Mostly proprietary parts, but very well done by all accounts, and priced accordingly.
http://www.heidts.com/
By all accounts their latest stuff is very good.  I spoke with Mary and Dave Pozzi at SEMA about heidt's car, which Mary raced at a suspension challenge super chevy magazine did.  She thought the Heidts stuff performed very well.  I dare say surprisingly well.
I can't think of any other 2nd gen SF I'd buy.  
If stock frame is the eventual choice, perhaps call Keith 
http://www.customworksproducts.com/ or Mark at 
http://www.scandc.com/suspensions.htm
Hold a gun to my head today I'm going AME. I like OE parts a lot.  All 3 options are better than my driving ability.