I am running the TeraFlex kit 2 years now and it works just fine. I bought it used had the rotors turned and bought new pads.... thats it. A rear disc conversion is not necessary as the older drums will work just fine. It is really a matter of can you afford it or not. I did it because I wanted to improve my 44 as best I could.
I went with Ford Exploder disk brakes from a 97 and then used e-brake cables made by East Coast Gear for the swap. The setup works absolutely fastastic and the parts were cheap from the local wrecking yard. My largest expenditure was the e-brake cables at about 70 bucks, but shipping is free. I never kept tabs on my exact cash output but it wasn't much over a 100 bucks. The best part is replacement parts are easy to get at the local auto parts store. Links are below.