If you want +P+ work UP to it......not the other way around.
I was thinking the same. A bullet 7 grains lighter than the data for 147 gr. bullets won't raise pressure unless there is something about these bullets we don't know...I agree with using 147 data. There will not be extra pressure unless you seat them extra deep in the brass. There will be less pressure in all likelihood.
This. Start low and work up.
Best option, if you want .38 Super performance, buy a .38 Super.