I'm as old as dirt so late 70's early 80's when they started noise restriction here in Oregon. Those early days prior there was no restriction on speed or noise... I look at drag boats as the unlimited end of the Hot Rod days. But, i do believe things... may have changed since then.
Most of the big block flats with 18% gears ran +70 mph! Most guys I knew ran Chevy high 80 low 90mph if they stayed off the cavitation plate.
Young crazy period of my life... work all week, spent all our money on the weekend. Beer, Gas, loaf of bread and hotdogs.... the weekend was all on the water... slept in our cars or back of our truck. Up early on the clear smooth water skiing, tubing during the day. Big late-night fires. Usually there was at least 5-6 boat up there with us every weekend all fast v-drive... well one guy ran 9% so maybe 65mph 1967 L88 427 with two Holley 650 double pumps on tunnel ram manifold. he had the original factor alum heads. He was more skier... less crazy than the rest of us.