If you ever run into this again, you are safe using similar bullet specs above your current pill's weight by say 5 or 10 grains. If you look at any loadbooks at all, you'll see there is a consistent trend in the lighter pills having more powder under them. Sorry if I'm playing Capt. Obvious here. Therefore, by picking a spec on a 155 grainer, even at it's max, you would not exceed it for your lighter 150 grain projectile.
That said, I know how you feel, not having published data does make one's decisions more tenuous considering we're talking guns here.
If you have future issues, be quick to contact the powder or bullet manufacturer. I had the same issue with a 165 sierra JHP for my 10mm and a Sierra rep got back to me in less than one business day with the information I needed to proceed.