One of the advantages of an SCT is that you can move the focus in and out by a lot through small shifts of the primary mirror. You should be able to solve your problem by releasing the mirror lock and turning the focus knob. Given that this is an old C14 any mirror lock will have been added afterwards so you will need to work out how to release it.
Anticlockwise rotation of the focus knob (as seen from the back) moves the focal point away from the telescope (at least in all the SCTs I have) but you can check how the focal plane is moving by looking at your projected moon image. It is a characteristic of this method of focussing that the effective focal length changes a bit as you shift the primary back and forth. Don’t worry about the mirror falling off the central baffle. The focus knob will stop moving at the end of its travel.
Once you’ve got a decent back focus distance you can lock the mirror again and use your Moonlite focusser for fine adjustments.