There were accounts from the 1920's and earlier of 400+ yard drives. Under the right conditions, people could go long.
But there are also a number of driving contests and measurements from the 1920's. It's clear from these that a very long drive was 250 and that averages (these were the best golfers of the era) were around 230.
However you want to frost up your glasses, they hit it a lot shorter than we do now.
Consider that there were some 7000 yard courses during that time. If you do the math, a course today would have to be about 8200 yards to play to the same relative length.
Bob