Actually, I have a hard copy factory manual for 3 and 4 cylinder engines and it goes into detail on rebuilding. If the ebay one is a true Factory manual, you can not get better.
Rebuilding is really very easy and no special tools other than a flywheel puller, inch pound torque wrench and foot pound torque wrench are needed. I usually take about four hours to disassemble but I have done quite a few and can do them with my eyes closed. If you have never rebuilt any outboard, figure an extra 2 hours to disassemble and reassemble.
Before you ask: The stock bore is 3.375 and pistons are available in .010, .020, and .030 oversized. Do not try to go .040 as this leaved the cylinder walls too thin. Pistons are cam ground with a major and minor diameter. They are sized for correct clearance if the cylinder is bored exact to the oversize. SO. Let the machine shop tell you how much overbore the cylinder needs and order the piston in that size. YES--you can replace one piston and the engine will never know it.
Before you actually do the disassembly, "mike" the bore and double check to see if the scratch can be honed smaller. VERY often, a piston can be replaced by going through the reed openings and even with minor scratching, will deliver good compression.
The stock pistons are cast and have a semi-keystone top ring. It is common for these engines to break the top ring and drive it up through the top ring land. If you have the money, it would be a good thing to replace all four pistons with Forged aftermarket square ring pistons. I like Wiseco but there are as many opinions about them as there are oil threads or ethanol gasoline threads. Ultimately, it is your engine so do what you think best.
