Hi David, our B&S historian, Deejay, is away on vacation at present but we can make a start with some easy stuff. First, the numbers on your Briggs engine. It is 8 cubic inch displacement (130 cc), is from the first Briggs design series, has a horizontal crankshaft, a Pulsa-Jet carburetor, plain main bearings, and a rewind starter. (The model number tells us all that). It was made on 27 July 1988. If it is the original engine fitted to your mower (which is likely), the mower will have been made between late 1988 and some time in 1989. Being made after 1983, your engine will have electronic (breakerless) ignition.
Your mower's reel (the rotating blades) looks as if it has probably never been resharpened, which means the quite large expense of replacing it is likely to be a very long way in the future. I can't judge how sharp it is, or the condition of the bedknife, from the pictures, but if it is mowing well, things look positive. You seem to have got hold of a good example of the SB45. However you need to inspect the condition of the chains and sprockets, in case they are worn or rusted.
So far as dismantling and painting are concerned, let's see if one of our experienced SB45 owners is available to help. Steve, Deejay?