Fascinating question! During the eighties, the LSAT experienced significant changes, first away from a 200-800 scale (similar to the old SAT/GRE) to the 10-48 scale, which lasted until 1991. In addition, the eighties LSAT dropped much of the mathematical analysis that characterized the test before 1982. However, there were shifts in the corresponding percentiles and scaled scores, which was not without controversy at the time. The only histogram data I have available relates to the LSAC's 10-48 scale conversion to the 120-180 scale from 1992. Thus, it would be difficult for me to give you a conclusive answer. With that caveat, however, a 35 on the 10-48 point scale would be roughly a 65th percentile score. Now, the percentiles also shift periodically on the 120-180 scale. In general a 65th percentile score is roughly in the 155-156 range.
- 35 scaled score ~65th percentile 155/156 scaled score
Lastly, you should also note that the format of the LSAT was significantly different before 1991. Because the test format was different, any comparisons between LSAT scores then and now should be taken with a big grain of salt.
I hope this helps!