It will need to be examined by a competent gunsmith
22 Magnum Rim Fire
The Ithaca rifles are rimfire. Most are .22LR, but there is at least one .22 magnum.
Only if it's a .22 Long Rifle revolver. It's not compatible with the .22 Winchester Magnum Rimfire.
Inexpensive Italian copy of a Colt revolver. Value $75-$100 in excellent condition. Some also had a second cylinder in .22 Magnum- add $15 for second cylinder.
.223 inches for the .22LR, .224 inches for the .22 WMR.
No. The 649 was a 6 shot, and had two interchangable cylinders to permit the use of .22LR or .22 Magnum cartridges.
Small game can be hunted with the 22LR and 22 Magnum.
IF the revolver is marked ".22 LR" yes. If it is marked ".22 WMR" or .22 Mag" or " .22 WRF", then NO.
just the cylinder change
No. The .22 Magnum is not only longer than the .22 LR, but it is larger in diameter. The 22 WRM (its proper name) also has much more energy- and would not be safe to fire in a rifle built for .22LR.
Probabably 22LR. Have it checked by a gunsmith.