I have a Colt MT6400c that I bought less than a year ago.  Now that the ban is over I want to get the most out of it as I possibly can.  

I intend to have the barrel cut from 16.1" down to 14.5", recontoured to correct M4 profile, and topped off (permanant install) with something like a KKF 1.5" A3FSMS Milspec look flash hider to achieve a new overall length of 16".  I am pretty much up to speed on this part.

But...

I want to get rid of the faux tele stock and get a real tele stock.  I think I have settled on the Magpul.  Would somebody who is familiar with my rifle tell me what exact parts I need and where to get them for optimum install of the Magpul stock on my rifle.  I have been told that my rifle has the carbine length spring and the heavy duty "H" buffer already.  But I guess the buffer tube will have to be replaced.  Any and all help will be appreciated.

The magpul stock will come with all the parts you'll need.  Just follow the instructions that come with the stock to install it then use your old buffer and buffer spring.  Just be careful with the buffer detent and it's spring which will launch themselves into orbit when you remove the old stock.  And be careful with the takedown pin detent and spring which will do their best to escape while you're distracted by the buffer detent and spring.  Doing the assembly and disassembly with the rifle in a clear plastic bag so that all parts are contained is a good idea.