There is no "correct" tint, color or tone as the mix was always changing but typically (in 68 at Dearborn) in a general range it appears. SO since you still have your original you will need to have that color matched.
Couple of choices here - If your in a bigger urban area often paint suppliers (paint shops) will come out with a camera that reads your color and spits out a formula - clean the spot well and give it a little rub with cleaner/polish to remove any build up or oxidation.
Second choice would be to start with something like a early 2000's VW gray and tint it till you get something that is dead on. This will take allot of effort and trips but its what needs to be done if you don't have the other option unless you can take the body to the paint shop for them to match it the old way
Finished product with be basically a fairly shinny paint. Remember that from the firewall forward you will still be looking at a red oxide base likely that will show on areas in the inner fenders and from the bottom of the car - along the frame and in the suspension pockets and the like
Hope this helps a little
