T5 will hold up fine behind your 283, or anything for that matter, depending on how you drive it. If you want to do burnouts at every light - then, no, don't use a T5. If you don't drive like that - then a T5 is fine, and a fun install. Here's my thread for how I did it in my 66, same logic applies to a 67-72. Maybe you'll find some useful info in here:
http://67-72chevytrucks.com/vboard/s...d.php?t=482069 The only thing I'd do differently is to purchase Vintage Metalworks T5 adapter plate rather than make the custom one you see in this thread. It wasn't available (or I didn't know it was available) back when I did this swap. The T5 drove/shifted like a dream, MUCH more fun to drive. I tried to make it look like an old 60's Hurst shifter setup, but lots of options as to how you co do it for your own taste.