Have a look at the FS-60C manual; there are system charts showing you which pieces/extensions are needed with various configurations:
http://www.takahashiamerica.com/manu...C%20Manual.pdf
Since it's a (relatively) short focal length scope, the field curvature is fairly severe - especially if you're thinking of mounting your 5DmkII on it. You'll probably want to use the dedicated
reducer or
flattener to get reasonable stars.