Lucas, I used some stuff called Durafix. No flux. There are some videos on you tube about using it. I have a $3500 tig welder but I wanted to try this stuff so a dude in his garage could do it. So far it has worked well. If you decide to try it let me know and I'll give you some pointers. I have documented this extensively on the AirVw and Aeroconversions groups on yahoo. "Fat Fin Head" is the name of the thread. I see you are a welder so you might be better off tig welding them or mig with a spool gun but without a doubt you should do the mod. Look at my numbers on the groups. I've had all kinds of trouble with temps, until I did the mod. Read all you can and you decide for yourself but I can tell you without question you will glad you did it. BTW, I use mofoco 042 also and they are hands down better than the 042 chinese stuff from Great Plains. I tried em both.
Wayne