Yes, but the narrowest point on the barrel is usually only a few inches back from the muzzle. The slope at in the portion of the barrel you will be sliding it around should be very slight so, as you indicated, it doesn't matter much.
Now, sight selection is going to have some bearing on this or any installation. Don't go crazy with tall or missmatched sights and such.
Just lay a straight edge from the breech to the muzzle and give it a look. Enjoy, J.D.