If the SCCA Street Modified class rules would have allowed it, the first engine choice for my 83 Celica would have been an LS1 for all the right reasons.
For a given hp/cu in a DOHC 4 valve setup can be a llittle cleaner and slightly more efficient, but with modern port design, the difference is actually quite small. A second advantage is likely a wider power band because you can used less aggressive cam timing with the larger curtain area to achieve the needed flow. Just look how flat the torque curve is on the 1UZFE. And thanks to the much smaller heads on a pushrod 2 valve, you can easilly fit alot more displacement in the same space, and make a ton more power, thought it does burn more fuel.
There are also other advantages to the single cam down in the block. The Corvette design team has been toying with OHC engines for many years, but the simple truth is, the C.G. of the pushrod motor is quite a bit lower. Cams are heavy, and sticking 4 way up on the heads does make a difference. Rocker arms are pretty light. The LS1 and later variants are amazing motors that pack huge power into a small light weight package. For a total luxury car, the UZ is sure smoother, but will never touch an LS1 at the drag strip. With some mods and forced induction, the 1UZ can also make serious power. The original 1UZ 4.0 litre has proven to be as strong as anything out there to take boost. Too bad it is such a small displacement.