I must respectfully disagree with GTjoey ... I replaced may 3.54 rear in my '68 OTS with a 2.88 and LOVE it.
It is smooth off the line and lets me cruise at Texas speeds at a reasonable RPM. I can probably lay rubber in 1st and 2nd, but don't try. The key question is: What is your highway cruising speed? ... Mine is high. It gets me to where I can enjoy the ride quicker ... the hill country.
Bill