Well, where i'm from, you buy a used long block- everything comes with it. Unless you are buying a long block from a manufacturer, why wouldn't these things be on there? Including the balancer, flywheel, water pump, and all the covers. Guess you should be more specific as to the term "long block".
The engine builder will build to your specs and do complete engines. As with a lot of builders, $$$$ is my limiting factor. In fact Zipper Motors will build the car turnkey for a price. My wife and I are putting most of our extra income into the mortgage right now, so the house will be paid off when she's ready to retire in a couple of years--24 payments left. "My Car" gets the left overs and money from second jobs.
Look for a donor car/truck with a a good drive train and use it until such time you decide to disassemble it to build your project. Or watch the papers..do you have access to: www.cruisintimes.org/
and see if you can hook up with something you can use.