my money would be on a scarebird kit
for about 500 bucks you get a set of bracket that replace your drum mounting plates
a spacer ring to center the disc on the spindle
a set of discs drilled to for 5 on 4 wheels
a set of calipers that mounts to those brackets
a new pair of brake hoses and thats it
the ONLY thing need is longer wheel lugs
(and you can piece this together by ordering the discs, calipers and hoses off rockauto and probly get it for half the cost)
now, there are other options available but they will cost more, move your wheels out further (the scarebird kit only ads about 1/4 inch to overall track) and may need different wheels