It will be tight. The C14 tube is about 1m with cameras, no dew shield. Hope you have extra Cw's. The PMX is also a big mount. Graham
http://www.iceinspace.com.au/forum/member.php?u=5952 has an MX in a smaller dome and can probably give some indication. I'm building a 3m 5/8 dome to house a PME II with a C14. That will still be pretty tight but its a complicated system.