Like Poncho has said, you have to have a mid plate, or at least the mid mount batwings some of the circle track guys use, to support the rear of the engine. It will be too great a distance between the front of the motor and just a regular transmission tail shaft mount.
Pro's are it frees up a lot of header space, provides a very stable place for accessory mounting, and takes large HP loads off the side of the block and puts it into the much more solid front bulkhead of the block.
Con's are the needed mid plate, you have to watch the plate for cracks over time(aluminum fatigue), and you will need to fab up a lateral link support to keep the engine from shifting forward or backward under acceleration and braking, which will flex the plate and lead to cracking. Most use a hiem joint link(rod ends and threaded tube) from one of the old motor mount bolt locations on the block back to the frame near the drivers feet. Very similar to a diagonal link on a set of ladder bars or 4-link rear.