yep thought it would be 91vxl will be 3/8 low pro, easiest way to tell if its a rim sprocket or no is if you can see the teeth or not a rim sprocket is round with gaps for the drivelinks to sit into while a spur sprocket(intergrated to clutch drum) will look like a star when viewed from the end.
going from .325 to 38/low pro is definitely a step backwards and depending on the saws engine size may not be recommended for safety reasons, small chains can only take so much hp before they stretch excessively or potentially break,
post a couple of pics of the setup and the model number of the saw
