I've had DOHC and SOHC on one car, 1990 Mazda Protege. At first It was DOHC and it wasn't running right and had problem with blown gaskets and weak accelerator. So I swapped out head and timing components (idler, pulley, water pump cover, and main bearing cover) to covert it to SOHC. It ran better. I used Ford cylinder head on Mazda engine (Ford and Mazda uses same engine. Mazda have Ford emblem stamped on valve cover!!
).
MY friend told me that I was using wrong kind of torque wrench (one that have long arrow with dial on handle). He said that I should have use Click type torque wrench for more accurate tightening. That's why I had problem with Protege cylinder head. Since it's an aluminuim head and Iron block. I should have loosen and re-tightened it between 500 to 1K miles for good seal.
That was interesting about OHV and SOHC and DOHC. Yes I agree that OHV put out lot torque on low rpm.
Catty