Hello Zed,
You have a Newtonian telescope there. You've described the Primary mirror as being 6" across but to rebuild the scope you will need to have some idea of what the focal length is.
Why?
You indicate that you would like to replace the focuser, the part that hold the eyepieces, so that it can take standard 1.25" eyepieces. To do this you will need to know the focal length. If you could tell us the height of the focuser we might be able to work it out without you getting the mirror out yourself, but from the figures you've already given it indicates its around an f/8 or 1200m long (I'm going to skip stuff here and recommend that you look up the terms used to describe telescope parts and also how Newtonian telescopes work. There should be heaps of info around)
A 6" scope will introduce you to the deep sky, with open clusters, globular clusters and some of the brighter galaxies. A 6" f/8 usually does a good job on the planets, too.
Making a dobsonian mount is the easiest way to go.
