I too would start with the 5.8 grains of Unique.
I looked up the Speer data.
Strange, they show a spread from 5.6 to 6.8 of Unique for their 150 gr. bullet.
Yet list 7.1 to 8.0 of Unique for their 155 gr. bullet.
I think I would skip on that data.
Did you ever think of using 231/HP38 or TighGroup?