I have a 65 mustang V8, with 5 bolt drums and an 8 inch rear end, all stock.  I understand that a disc brake swap is the logical course of action.  Has anyone tried mating a larger drum system to the mustang spindles and rear end?  I am mostly interested in the rear end brake change, but I am very curious about the front end as well.  Any ideas?  

If the rear drums are 10 x 2", there's no real need to change them.  Bigger drums in the front would be a waste IMHO because they will still fade and they would upset the balance of the braking system.  There are a couple of posts here on the subject if you search a bit but mainly the front disk swap from a Comet, Maverick, Granada, etc works well because the cars have similar weight, braking system layout, etc as the early smaller Fords.  If you want to really get it hopped up with big  brakes then you might as well go to a full aftermarket setup.  You can use lots of factory parts, just depends on your budget, free time and inclination.