This is how you manually verify it's a 1.5 ratio drive
Yes most 1.5 are used on SBC V8 light boats, Twin SBC V8 heavier boats, and also BBC V8. All depends on HP to weight ratio. If it gets heavy enough it ratio will go low (1.8, 2.0, 2.2)
We know it's 1.5 so don't worry about that part.