I'm not sure what you mean by a "backwards mounted Lyman Aperture sight", but Model 70 sights are designed to be installed on the left side. If you mean that a Mauser sight was installed in place of a Model 70 sight. there are plenty of Lyman 48 sights available on the used market. If you can't find one, I'm sure I have one I can spare. The improvement in accuracy over the open sights is significant.

I used to shoot competitively, and my rifle of choice was a pre-War Model 70 based .308 Winchester target rifle. The pre-War bolt action is incredibly smooth, even compared to other Model 70's, and for that reason I have always preferred them to the post-War version. I have shot more than one perfect score at 200 and 300 yards, rapid fire, and at 600 yards, slow fire, with that rifle, using iron sights.

The safety has never bothered me, and even if it did, it is easy enough to alter it to the other side with an after market Tilden safety, which shouldn't be hard to locate. A Model 70 collector might be happy to swap you one for your original pre-War safety.