Walls and Ceilings - How to vault a ceiling (or "it landed on my head")

We have a post-and-beam house built in '68 which has a fairly shallow pitched roof (run 3 rise 1) constructed of 4x8 rafter beams set approximately 70" oc. (no ridge beam.. they just butt up against each other at the peak). the roof is "sheathed" in 2 x 6 tongue-and-groove boards running perpendicular to the rafter beams with a metal roof above that. There are horizontal 2x6's running from one wall plate-rafter intersection to the other (collar ties?) at ceiling height which is an abysmall 7'4". Besides the 8 collar ties under the eight sets of rafter beams there are more 2x6's (ceiling joists?) at about 18" oc filling in the gaps. These joists and the collar ties run the entire span (23') with no support from below.
The ceiling is currently paneled and the goal is to remove the panelling, put in new collar ties immediately above the existing ties and remove the old collar ties (raise the collar I think it's called) and hopefully remove the "extra" joists as well.
The span is 23'2" total (11'7" per rafter beam) and we want to use 4x8 or 4x6 beams for the new collar (douglas fir or red cedar) and leave the whole thing open when we're done.
It seems reasonble but I look at this and can't figure out what's holding the peak up besides the two roof beam leaning on each other and the skimpy 1x4 post which looks like it should split the 2x6 if there where actually any weight on it... probably the inverse. the 2x6 is hanging from the rafter-beams? Does this look like it would work?

htp://www.the-davies.com/the-davies/images/RoofDrawing2.JPG (http://www.the-davies.com/images/RoofDrawing2.JPG)

The drawing is of the current structure (side view of a single rafter-collar assembly and top view of the entire roof).

Thanks for any thoughts.

Any thoughts would be appreciated.[/