Arty is your engine original to the car? Sounds like it might be by the blocks date code. If so it's nice to keep and use the original engine and just keep whatever parts you don't use. It's only original once as they say. It's normal to not see a casting number on the block from 68 up. Not a big deal as they were generic anyway for the most part. What kind of budget have you set for this? There are a few different ways to go.