I don't know who told you that a flathead engine is an easy build because it isn't. You first have to find a good block and then have it magnaflux to see if the block is cracked.. I'm rebuilding a 53 merc block and believe me it's taken longer and more expensive than I'd first though it would be. I've worked with flatheads since 1958 and I love them and yes you can get a nice 250Hp engine built like thesals says, but it's going to cost you some big $$$$$