Use up to date data, the IMR powders are not the same as they used to be.  I'd recommend using Hodgdon's website.  Even their data is a bit old as they're using CUP rather than PSI.  Start low, work up.  You may or may not have feeding problems with the spitzers, might want to make a few dummy rounds to try your bullets first.  Nosler has some fairly recent 30-40 data too, no pressure data, but their loads wouldn't be above the SAAMI max.