If you had a big old Marshall you would not need an overdrive, those peddles where originally built so people with lesser amps could try to copy the Marshall sound or other big real amps. The peddle you’re looking for, to get that wave or ocean swoosh would be a phaser. When I bought mine years ago they were called phase shifters. If you have a choice, try a few of them before you buy.
If I was trying to get the “”tone” I would start with my guitar on the treble pick up. Thinking the amp dials use 1 to 10, Treble at 5, Mid at 7 Bass at 9. Reverb about 7. Amp set to do it’s best to sound like a Marshall. I think he used more bass, than most people used back then. Starting with your guitar pickups, start making small changes looking for the tone.