I just purchased a boat that has a Volvo B20 4 cylinder engine in it with a Volvo Penta 270 outdrive. The shell of the boat, the interior, and the outdrive look in great shape, however, I'm needing to either fix or replace the engine. Someone had taken the head off the engine and it sat in the weather and rusted. Would it be better, easier or cheaper to tear the engine apart and rebuild it or should I look into replacing it?<br /><br />My other concern is that I don't feel I'm going to get the performance out of the 4 cylinder engine that I'm going to want; the boat is a 21' bayliner. Are there any other engines that will match the outdrive where I can get a 6 or 8 cylinder? I know I'll have to change the outdrive over to accomodate the larger engine and gear ratios. Anyone have an idea?