alternative 4spd

Does anyone here have an R154 behind a 360? You make it seem as easy as finding the bellhousing and tranny and making a little room for it and bolting it in. What else is involved in this? The transmission mounts would have to be custom made wouldnt they? This idea intrigues me greatly, but I'm wondering how much actual work will be involved. Also do you know how much hp an R154 is good for?