FWIW & IMHO:
Just for comparasion's sake, I have had 5 '86-'87 turbo Buicks, and none of them had a powermaster that looked like that. Seems to have the updated accumulator ball & grey switch, but the main body should be silver color, or approximating a silver color, and the gold on the electricial motor unit shouldn't be quite so gold. The gold color on the standard, as in usual or normal, and not as in Standard manufacturing Company comes from a Cad plate or cadium process, or a process called iridite dip, which is pretty standard in the manufacturing or aerospace industry for minor rework or touch-up for cad plated parts. Yours almost looks like a gold colored/tinted applied paint. I will attach a picture of a unit that is unretouched and a brand new powermaster unit of known origin. That is probably from a different model of Buick, as you say, but it is not from a turbo Buick.