If you want a .45 Colt BH, by all means get one. It will probably have slightly tight throats, and this can be meaningful or not. Get the gun, shoot it for awhile. Every gun is different.
I have .45 BHs that shoot just peachy right out of the box. No, a .452" bullet will not push through the throats. So what? Excellent accuracy and leading is not a problem. I had a Vaquero that proved to be a little lax, and it improved things to open the throats up.
So, get what you want. If you think the gun not up to muster, CAS does excellent work at a very reasonable price. If you want to live on the upper edge of "Ruger only" loads (particularly those found on the internet-it's your life, take your chances as you will), opening up undersized throats might lower pressures a bit.
BTW, the absolute worse revolver I ever owned accuracy-wise was an OM Super Blackhawk with perfect throats, For whatever reason, it remained a shotgun no matter what load I tried. The second worse was a .357 OMBH. It had throats of all kinds of variety. These are rare, thankfully, but maybe you see my point.
Get what strikes your fancy.