I know a hand full of people right now building Panheads. The topic that comes more often then not is, Exhaust Leaks. For people with money the answers is simple, "buy STD heads". For the rest of us, its even simpler!
Start with a stock 1-3/4" exhaust pipe and insert all the way into the port making a "gunner pipe"
next, Cut off the exhaust spigot of your pan pipe
next, place spigot onto stock pipe "gunner pipe"
this is where things get tricky... Panhead ports are not perfectly round, but they do have a sweet spot. Slide your gunner pipe into the port then slide your spigot over the port. turn both till you find both pieces starlight and squire to each other. Make a couple marks on the head and pipes. Where the pipes naturally fit, is where it will stay. Start welding in place. Make sure you weld goes as far around as possible. After cool down, it will still be tight! Keep your gunner pipe a little long to grab it and wiggle it off and on. After you finish welding and cleaning up the piece, make sure to re-in line your marks when putting the piece back on (it will most likely not fit any other way).
Trim it up and re-weld your exhaust. At this point you probably don't need exhaust clamps, However put them back on and if anyone asks, tell them your still saving up for STD heads and mumble something about your no good pan... They will understand!
Now, go Faster!!!