I had a the shutters replaced in two different 1DmkII's a few years ago by CPS and the cost was around $300. I can't imagine that it would be much more than $400 today. Canon still services the 1DmkIIn, but not the mkII.
Yea. repairing a shutter is not the easiest thing to do even for people like me who know what they are doing(do mods and repairs on all kinds of cameras)...but on a 1D series? even I will send that into CPS..
just sayin..
Good luck, and whoever said "I pray for the camera.Let me know after ICU." was dead on!! you are asking for failures and issues unless you have done this MANY times in the past, and have some experience with handling very sensitive electronics.
And if you think that means just knowing how to not touch caps or other parts to keep from shocking yourself, you need help and have no clue what you are doing.
Honestly, I admire anybody looking at doing this themselves! I build and re-build many things and have never really thought about doing a shutter, but crap, I send about 4 bodies in a year to CPS for $350 each on top of the $500 membership!
Maybe I should look at getting a $100 pack of tools and lighted magnifying stand!
Why should we doubt somebody's ability to tackles something like this. It may be right up the OP's line of capability, even though to the rest of us seems daunting.
for the camera.Let me know after ICU. 
