Sorry I did not reply sooner, I've been out of the loop for a while for a number of reasons, one of them being that I have been out of town for work for most of the last three weeks. Anyway, Ed beat me to the punch, and was able to answer your question. Thanks Ed!
Like Ed, I bought both the back plate and the chuck at the same time. The back plate for mine was also pre-drilled, I only had to cut the register on the back to fit it to my lathe. Oh, and yes, a chuck key came with it, which is standard practice if I recall correctly.