I did something similar on my old IH Scout. Worked like a charm! Unfortunately, the compressor was on it's way out anyways (bearings were out; sounded like a dying water pump), but for the year or so that I had it, it worked quite well. FWIW, I had a shop evacuate the system completely first, but I don't think they went so far as to flush it. And the R134a was quite cool; worked very well for this area and going up and down California on the I-5.
Just my $.02...I probably used the same kit, BTW.
