It really does depend on what you are willing & able to do yourself. 55-60 avg sounds about right. You can also really get crazy on an engine, especially an FE, without trying too hard.
I think the best way to estimate your cost is to put together a spreadsheet. It will take you some time but write down everything you want on the car then write down the corresponding costs from the ERA site, paint shops, engine builders & so on. Don't forget shipping
. Once you have a base cost you can decide if there's anything you can do yourself to save money or maybe cut back on some of the options to get inside of your budget. Chances are you will end up with a little extra cash during the Lead Time to add anything you really want.