I've got a mild 390, estimate around 400-450HP, that has developed what I believe to be a rod knock, though I'm still in the diagnosis phase (fairly certain, though--unfortunately). I'm debating whether to try to purchase a decent running engine, or just rebuild the short block.
There are so many variables to consider, but cost, time, and quality are at the top of the list. My Galaxie was built by the previous owner with GT heads, so the manifolds/exhaust are a limiting factor for purchasing an engine for direct installation. Of course there are different ways of dealing with this, but I've been hoping not to miss the driving season this year, but that may not be practical. Obviously, going through the short block will likely eat up the driving season (or more) given that there is only one machine shop in the region I'd trust, and he is always extremely busy (I'm not the only one who thinks he's very good at what he does). I'm testing the waters here, exploring any possible options.
I'm in the Bowling Green, Ohio area.