Welcome to the board.
Since you are new,... I will answer your question by say,
"this question gets asked about every day of the year". Ha.
Search around in the suspension section or look at this thread:
http://67-72chevytrucks.com/vboard/s...68&postcount=4
71-87 front suspension is a good disc brake source.
71-72 coil spring rearend would be a bolt in swap.
73-87 rearends can be made to work with a little fab work and welding.
Again,... WELCOME to the board!