For historic reasons, people tend to think that side-valve engines possess unlimited low-end torque, but this isn't the case. When ohv engines were introduced, they tended to be a bit more expensive, and a bit faster because of the more advanced breathing, but more fragile because of the then-new metallurgy. Hence the fallacy of the "slogging sidevalve", born of natural conservatism, lack of development and economy ( although the higher fuel consumption and valve/cylinder wear of the sidevalve rapidly devour any savings in initial cost, several times over )
They are also resistant to harm, in that a stuck valve in an ohv engine is a disaster but a stuck valve in an sv engine isn't, and they are generally so robust and under-tuned that no real harm comes to them, whatever you do.
45s need to be worked quite hard to get anything out of them, and fast side-valves are almost like two-strokes. That's why the 4-speed conversion for the 45 is so successful, by enabling yoiu to keep the revs higher and more constant.
Shoot, a man could have a good weekend in Dallas with all that stuff...