I personally think 50/55 is a lot to ask of a bike that was originally designed to go 30 at best, especially if you're unwilling to really get your hands dirty. If you live somewhere flat, you can probably build a mid-40s bike without much hassle- there's plenty of info on the forums.
pushing the 50 mph barrier will need expertise, patience, and a decent amount of work or else your flashy new kit will be a paperweight or your face will be a 100ft smear on the pavement. If your friends' bikes are hauling ass, why not ask them for a hand?
You will still need to rebuild the whole engine even if you're only aiming for 40mph. A 4 decade old cruddy worn-out crank and bearings are gonna give up the ghost pretty quick when they start screaming thousands of RPMs higher than it ever went in stock form. You'll still need to get into fiddling with clutch tension and ignition timing, too.
and all of that stuff is still worthless if your bike can't go 40 to ZERO quick and safely enough to avoid eating shit. Or even just maintain speed safely... your raggy old pedal sprocket gets gummed up and your pedals turn into egg beaters, your crusty-ass wheel bearings lock up one wheel and throw you into traffic, your improperly tightened forks fuck up in a corner, your glazed-over dried-out brake pads do fuck-all, etc etc etc.
i do not claim to be an authority on Mopeds™ but just don't let your ambition outrun your sense. You will need to clean your tank (degrease with soap & water a few times, soak with vinegar for a few days and use small nuts/bolts as abrasives and shake the shit out of it), you will need to clean and repack or just replace bearings, some moped things are inevitabilities.
It doesn't hurt to ask and research stuff, and people here will probably say I'm being pedantic about dumb shit (build it ride it break it fix it, its just mopeds right?), but at the very least you can't really just throw a kit on it and call it a day (edited)