gbehrman,
I believe you are saying that it currently has a one piece base on top of the receive with the redfield scope and in addition it has been drilled and tapped on the left side of the receive for some kind of mount, please confirm?
The question about number of side hole is a good one and may help identify the mount. Also can you give the manufacture date of the rifle, or if not then the serial number? You can X out the last couple, just looking for the range to determine make year.
Being the 300 H&H this would make it a long or magnum action which is more desirable however all the holes can detract from the value. It sounds like it is not necessarily a collector gun so the market is a user and or a rebuilder who typically are looking for a bargin.
If I were you I would do my research on gunbroker then figure out what would make you happy and then go for it. If it sells you will be happy and if it doesn't you will also be happy because both were based on your happy number.
