That's right. In later years, base Firebirds had 1" front bars, TA and Formula had 1-1/4" front bars.
For the rears, base models had 9/16", regular TA and Formula had 5/8". WS6 TA (78+) and Formula (79+) had 3/4". Any could be swapped about as required with new bar and bushes to match.