1-I don't know about Schumacher mounts if they make any, the one I did, we made an engine plate that sits on the front frame rails. If you put stock type mounts in, there isn't really any place to run the headers, so to do it right, you will need to modify the front frame rails slightly for a full plate. We actually made about three engine plates before we were happy with the position of the engine.
2-392 hemis are like 340's with hemi heads that don't flow like big hemis. They CAN make big power, but they require lots of work and money to do so. Typically a stock will drive just like a stock 340, thats 100lbs heavier if left stock. They don't make a ton of hp until you really ut some money in the heads. Check out the flow numbers on Hot Heads website for stock heads.
3-They are not cheap to build. For the same money you could build a 426 hemi. The headers being one of the bigget expenses as well as the transmission adapter. In our case even the pistons were custom and cost around $1100, or the same price as the custom headers did.
4-The only parts you re-use are the heads and valve train, block and crank, and the valve covers unless it came with the dual quad intake. Other than that, your going to be buying a lot parts.
