I also had a Dakota from EMF years back, somehow got lucky and it shot to point of aim with 250/255 gr bullets. Also like the the exact load you listed with unique, it seems to be a good kickin around load for most chores. If it shoots to the left, you can have your barrel turned in just a wee bit, if a smith by you has a barrel vice, or you could try it yourself if you feel up to it. You wouldn't have to move it much at all, just a little bit of a tweak really moves point of impact a lot.
Since it shoots low, your lucky there, you can file down the front sight a bit to bring up the POI. The Dakota I had was real accurate and gave nice groups. As I remember, the back strap was brass...but they had something on it that looked like black chrome??? It's been awhile, maybe 13 or 14 years ago. But I remember the insides was pretty much like any Colt and could be worked on if you wanted, and for the money it was a real nice revolver for walking the property I had back then. I think after you get it shooting where you want you'll be happy with it.