I've swapped in T5s before. I would NOT put it behind a "built" 350 (or torquey 292, unless you plan to not haul with it and do plan to baby it). I write that as "built" in quotes not necessarily because it's built, but usually folks that refer to their built this or that also usually like to do burnouts...
T5s are NOT made for that, I don't care what our Mustang buddies say.
The only benefit of the Camaro trans is the input shaft - i.e. no need for a spacer plate. But then you have the added cost of finding a tail shaft housing from an S10, which often means buying an entire extra trans - because these are getting a bit harder to find as everyone and their brother is doing this swap. If you HAVE a Camaro trans, then sure. Or if you HAVE an S10 tailshaft - then sure also, makes sense and IS the best of both worlds for ease of install.
Strength-wise, a Camaro box is not necessarily stronger. WC and non-WC trans were available in both Camaro and S10. WC is stronger and has some bearings on the countershaft if I recall - but it's still not a strong trans if you're planning on more than 1 burnout - I personally would not put it in a full size truck with a V8 (even though I kinda did that in my little swb 66)
Like Tim suggested, I'd stick with the 700R4 also, personally - am assuming it solves your desire to not hear your gears screaming - close to the same o/d ration as the T5 and other o/d manuals. I got lucky with my T5, it was a WC from an S10 and had a mech speedo drive - pretty much as good as it gets when scrounging a used T5 - it was a swap meet find. But you NEVER know what you'll get for sure unless you really rip it apart to inspect it. I did that only because accidentally stripped a bolt in the aluminum and shavings got in the box in the heli-coil install.. Duh. But, like I said, I put it in a tiny 66 swb and babied it - so it did fine in that scenario - but I knew I would not be hauling anything and I'm old enough that burnouts aren't my bag anymore (well, ok, not really, I was just afraid I'd munch my trans...)
Here's a link to the swap if you're still interested (i.e. if we haven't successfully talked you out of it yet) - this for a 66, but same applies for others.
http://67-72chevytrucks.com/vboard/s...d.php?t=482069
EDIT: one more note - you should only use a Camaro S10 shifter on a Camaro tailshaft hosuing - it has a built in cant or twist in the mounting train and the stick has a kink in it in order to make it come up straight thru the offset console opening in a Camaro. So, even if you use a Camaro main gear box, and an S10 tailshaft housing - use an S10 shifter also (or, what I mean is a shifter designed for an S10). Lokar makes a great stick that fits nicely in a Hurst shifter setup - round stick, etc. Unless you want the flat Hurst stick, then just stick with it (so to speak). Choose the stick carefully though, unless you have buckets - need to plan for seat clearance.