Are rear sight inserts for the pre 64 Model 94
available anywhere?

As I noted on another post, my rifle was shooting high and to he left. I now have the "to the left" part taken care of. But it continues to shoot high. I have no more downside adjustment on the rear sight and I don't want to change the original front sight. so I was hoping I could buy an insert with a much deeper V in it.

There are various rear sights that may have been on your pre 64 model 94. If you have a higher buckhorn version you could probably switch out to a flat top version or related series sight such as the semi buckhorn 22-g which often times was original to the 94 and very well may be the original version.

I don't know much about 94's as I am mainly a pre 64 Win 70 man, but you may want to research what was supposed to be on the gun in the first place. Winchester has been known to put substitute parts on to get guns out the door to meet quota. The front or rears on your gun may not be correct to start with. Yours may have a substitute front sight that is a little low. Win could have done it or if you are not the original owner, it could have been changed by someone else, especially if there is evidence of a peep sight installed at some point.

Also you may need a shorter or lower elevator that allows further travel for the rear sight. Some people remove the elevator completely.