If I remember right, to keep within the law, your low beam's maximum output should be 55W, and the high beam at 60W.
The third link you posted has all the info you need, in the first post.
Upgraded wiring harness is the first thing you ought to consider. This will vastly improve the output from your sealed beam headlights, as well as the H4 bulbs you are converting to. If you can follow the instructions, its fairly easy to make your own wiring harness, using parts from your local auto parts store. Auto Value carries everything you'd need.
Secondly, converting to H4-compatible lenses. You can get these locally, Auto Value until recently used to carry the Hella H4 conversion lenses, I'm not too sure who else carries them though, its been a while since I've looked. The Hella and IPF branded conversion kits are of much higher quality than the Autopal ones you can buy off ebay. I've tried them both.
Keep in mind, if you go wheeling in the mud, higher wattage bulbs means your glass headlight lenses get hot. If you nose-dive in to a cold mud-hole, the lenses will be prone to cracking due to the immediate temperature change.
Personally I run a self-made wiring harness with the Hella housings and IPF fatboy H4 bulbs, have also tried a set of 80w/130w bulbs.
As long as you have a good lens, and the right bulb-type for what that lens was designed for (ie. halogen, NOT xenon unless you get projector lenses) then you won't be scattering light up into the eyes of oncoming motorists on the highway, and will stay out of trouble.