If you can, before you do anything, use a high pressure washer with a degreaser and wash off the exterior, engine compartment and underside. If you dont have a pressure washer, drag the car down to the local coin operated car wash and take a roll of quarters. It makes it alot nicer to work on if you can get as much grease and dirt off of it as possible before your start tearing it down! Put a penatrating lebrucant on the bolts you want to get off a couple a days before you plan on tearing it down...it makes it easier!
I agree with taking lots of photos with a digital camera and bagging everything. What I found works better than bags is the containers that Gerber baby food comes in now. It comes in little plastic containers with plastic snap on lids. They work great and I put a piece of masking tape on the end with the description of whatever is inside (i.e. Wheel opening moulding screws). I like the baby food containers better than baggies because they can be stacked. I place them in a boxes that are designated for different parts of the car (Interior, exterior, engine compartment, etc).
Also, get a factory assembly manual and service manual. They will help you figure out how things come apart and go together.
I like to restore some components as they come off the car and place them on a shelf. I don't get as discouraged this way because when the car is all apart, you see a shelf full of parts ready to go back on the car, rather than a heap of parts that need to be restored sitting next to a car and body that need to be restored.
DISK BRAKE RELATED:
Regarding your disk brake conversion: The disk brake conversion is an easy swap from a '67 to '72 a-body. I would recommend the '68-72 since they used the single piston floating caliper instead of the 4-piston calipers used in '67. The '67 verson is more expensive (purists want it ) and they are more troublesome. Make sure you use the master cylinder and perportioning valve from the disk brake car.
I would add disk brakes if you intend on driving the car a fair amount and you intend on adding aftermarket wheels. I believe you will have clearance issues with the stock 14" steel wheels with disk brakes. I done several disk brake converstions and been happy with them all (always used aftermarket wheels in the past). I will probably keep the drums on the front of my '65 because I want to run the original steel wheels. Also, If it rains I won't be driving the car!
Enjoy the restoration and keep us up to date!