Jeff, cleaning aluminium can be done either mechanically or chemically. The most important point is to distinguish between sealing surfaces and other surfaces. Sealing surfaces - which just about always have gaskets between them - have to be kept smooth and flat, so both wire brushes and corrosive chemicals are out. I usually scrape them, but scraping aluminium has to be done carefully because the metal is so soft. Do not just put, say, the cylinder head in a cleaning bath, because it will probably cause pitting, including pitting of the sealing surface. You can brush it on, though, and wash it off, or you can use a wire brush, on the non-critical surfaces.
You can look forward to a lot of fun with your 92502. It is generally the same as my favourite small Briggs, the 92908. The differences are that the 92908 has a PulsaJet carburetor instead of a VacuJet (the PulsaJet has a fuel pump while the VacuJet relies on venturi vacuum to pull fuel up from the tank), and a vertical pull starter (like a car starter, it only engages with the ring gear around the flywheel when it is being operated - the rest of the time it just sits there completely inertly) instead of a radial pull starter (which has a couple of rather iffy features such as the plain bearing on the crankshaft, and the sprag system for locking it). Those Briggs engines are smooth, reliable, easy to repair, and parts are usually cheap and plentiful. (The Honda engines tend to have the first two features, but not the latter two).
