It depends on what your goal is and your desire to preserve your model 12. Standard pressure loads will put less stress on the gun and the terminal effects are not all that different from +P, meaning you'll not turn it into a 99% one-shot stopper with a high-pressure load. If you're just interested in pushing the pressure limits of the .38 Special, a steel frame .38 or .357 may be a better choice.
If the goal is a good defense load, sparing use of the 135 gr Speer Gold Dot Short Barrel will do the trick as well as any .38. Hope this is helpful.