Hi,
I currently hold a one time STC to modify the panel and flight controls for a Cessna 172, 1956, SN 28560, N5960A and the problem is the original yoke behind the panel is "T" shaped which blocks out almost all of the center stack area.  Changing to a 1964 or newer yoke from a 172 will solve the problem.  It fits exactly and has all the same leverage and is included with the 172 type certificate so you can apply or we can get an add on for my STC.  This will then allow you to build a new left and right panel and install a "center stack"  However I would go with the Garmin 600 series glass and the center stack with a new audio panel, radios, xpdr, etc... to suit your taste.  This makes a super clean installation and if you bite the bullet and rewire the aircraft to support the avionics you can add a circuit breaker panel, switch panel and new modern back up flight and engine instruments.  Done correctly you can have a full IFR C-172 and you will need to add the Vacumn pump and standby vacumn system as well as convert to an alternator that will give you much more power than a generator.  Yes it is expensive but well worth the effort when you have backlit and eyebrow lights on the panel instead of the overhead floods which are about useless. 
Contact me if you want more informationa and I will help if I can.
Jerry