i bought my nflip kit from a trailer supply co. it consisted of 2 spring pads and 4 u-bolts for a total cost of $28. i reused the stock shock mounts.
i have pics of my axle flip posted many times in this thread. you will get approx 7'' drop with this flip. you will need to c-notch the frame.
the drop front axle you have linked will give you a 3'' drop. and will cost you $500. add $500 more for a mustII kit and you will have a 7'' drop up front too.
sell your rear end to the guy in the post above to buy a welder