Single or Twin turbo setup for 360?

If you are just towing, and you don't need monster hp,
Have you considered Gears/torque multiplication?
An Overdrive trans, deep rear gears, and the right convertor, might be all you need.
If the engine build is still open, then for NA mode, I would suggest; high cylinder pressure and/or alloy heads and a bit more cam. You may not get to 400plus hp, but I fail to see the need for it; per your stated useage. Mostly, you just need some mid-rpm torque, and to gear it right. Whatever power you need for towing, the hi-pressure and naturally-aspirated 360 should be well able to make, just not at 2200rpm,lol.
Here is an engine that I am particularly fond of; The 360 sorta falls together like this, with small, closed chamber heads. This is a 230/237/110 cammed engine, which you don't need. You could easily move the torque peak down, with less cam, and increase it with ram-tuning. But your Purple is not the one I would run in NA mode. I mean you could, but in NA-mode, the top-end charge would be missing.
Of course if the engine is being rebuilt anyways, the stroker is a natural.

But, I mean, if you just want to turbo it, have at it.
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