360 Magnum Build w/ V Belt Configuration Question

The M1 single plane operating range is the “sweet spot” but it works fine on the street.
Why is it all torn down now; major changes or just little stuff?
RammerJammer75 shows how well the bypass hose will work in his second picture. Nice picture.
Just for reference, I will attach a picture of an M1 dual plane for Magnum heads and with Magnum bypass hose and thermostat.
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