i tried fixing the picture of the chart. let me know if it still doesn't work.
if your valve cover is buggered up due to rotating shafts, don't bother fixing. get a later model one with the fixed rocker shafts. i saw one recently in the for sale section.
650 cam can be used with standard rockers so it's overall a cheaper swap. but the tach drive gear and tack of a 650 or 750 will be needed to go with it as the ratio is different than that of the 550.
like all stock cams it's profiled for emission control; it will have a bit lower performance than the webcam or megacycle but i don't know by how much.
the performance cams use 550 corse with the standard tach gear ratio but have hardweld lobes, meaning you'll need hardweld rockers to go with them which pushes up the cost of the change.
i think i have a 126-00 that i could let go.