According to Chevy Hi Performance, May 2006 Issue
"For '68 Chevrolet released a larger low-performance 307 engine as a replacement for the 283. The 307 used a 283 bore and 327 stroke (3.875-inch bore and a 3.25-inch stroke). Production of the 307 ran until '73. By the mid- 70's, the automotive market began to change drastically and GM sought to raise fuel economy and reduce emissions"

So it is a possibility...