I don't think there was an L series head to date that came with dual valve springs, correct? If so it's safe to assume the head can be anything since there's obviously a hint of aftermarket modification there.
Shield gas makes a huge difference. When my brother used to work for the old metal shop, he would bring home huge Miller mig welders with massive tanks a shield gas, and I could (with no experiance) weld brake rotors together with no slag beautifully.
Using a H/F flux core, I weld like Indy.
Times are rough man. Wish you were local, we could have probably gotten all that over here for next to nothin. LOL
Good luck!
FYI, offer to trade labor for parts ;) You might find them for less
Also never really uploaded an exhaust clip vid when I got it all put together, so here you go. I have a leaky header, so it sneezes a little in the vid. Just haven't had time to fix that. Probably has a lot to do with why I'm loosing some torque and mid range power.
http://www.youtube.com/watch?v=j9CPzQmYOIw