I am a Pre 64 Mdl 70 fan to the max. Everything I have put together so far has been on a Pre 64 Mdl 70 receiver and am always looking. I think the control feed is the only way to go in a hunting rifle.
Here is a link to a shop that has a lot of Pre 64 parts so you can get that mag fixed.
Winchester* pre 64* Model 70 Rifle Parts
Is the serial number 500,000 or less
If you (or anyone else you know) are interested, I have a pre-64 mdl 70 in .243. I never used it, but it seems someone has. Unfortunately, the stock suffered water damage and is not in the best of shape but I had the rifle inspected and tested and was assured it works well. I'm looking to sell it to anyone interested. I also have a 1970 (or somewhere around there, I don't remember) mdl 70 in 30-06 that has been barely used. The original stock is in near mint condition and the bolt is jeweled, but it currently wears a hogue stock with the aluminum block. It comes with both stocks.
If interested, I'll send pics and ser. nos.