when looking at the classic Roland RE-201, or the Space Echo.
I see what your trying to do with a cassette tape drive,

ben there done that, as a kid., why reinvent the wheel.
the Space Echo schematics are out there.
take the time to see why cassette tape maybe problematic limiting you to only 3 tape heads
why 6.4 mm reel-to-reel audio tape loop is best tape echo you can imitate.
that best echo IMO is a empty room, following that is a classic plate echo - see video
the classic Roland RE-201, or the Space Echo will work as a tape delay