If it was originally chambered in .30-30, and not converted many years ago, it was NOT made in 1956.
The last .30-30 rolled out of Savage's factory in 1939 or 1940, when Savage began gearing up to fulfill contracts that it was receiving from Britain prior to US entry into WW II.
After the war the .30-30 was not reintroduced into the standard line up.
If you decide to change calibers to .38-55, you're going to run into a serious problem with the shell carrier in the magazine. It will have to be either replaced with one that is .38-55 specific, or the one you have will have to be reworked so that it will work with .38-55, which is no easy task.
Fortunately, it appears that the .38-55 carriers and the .30-30 carriers are, in those years of production, interchangeable. The problem is finding one in .38-55.
What's the serial number (XX out the last 2 or 3 digits) and I can tell you when it was made.