ok, when filling out the reg230 you should be able to transfer the old vin and new engine number over to a new registration card/plate. just make sure that you fill out the information as a transfer of ownership, since the vin may have already been registered. then you should be fine.
as far as aftermarket parts go, you are only screwed if you get pulled over. if you get caught speeding in the bike lane at 50+ mph, its a good chance that a cop will know you have aftermarket parts and will ticket you. for the most part they dont know whats up, so it shouldnt be a problem. DO KEEP IN MIND, however that aftermarket parts are for racing and performance use ONLY. not really for the street. it is not legal or suggested by this website or this thread to use performance parts. but there is a portion on performance tuning on this webiste ;)
as far as going to the local dmv? PSH, not worth the hassle or the risk of possibly getting your ped registered WRONG. if the dmv doesnt know what they are doing, they can possibly mess up your registration permanently. sure, if you need your ped registered next day, you can always take a chance but it really pays to mail it in and wait. why wait hours to find out they did it wrong? again, if you really want to ride while you wait for the plates, just ride it around your house. that way if you get pulled over, you can merely say you are working on the moped and should be fine.
POINTS TO REMEMBER
Transfer your moped with new engine with the reg230
merely fill over the reg230 as a transfer with the new vin and engine numbers.
Aftermarket parts dont need inspections
as it has been said many times, if you have aftermarket parts, keep it to yourself! dont mention it on the application and dont worry about an inspection. they DO NOT care about moped registrations that much. frankly, you fill out the paperwork and they send you plates. its no big deal. the only way to get caught with aftermarket stuff is being stupid. meaning, you are speeding 50+ mph in the bike lane in front of cops. dont be dumb!
AGAIN F!@# THE DMV OFFICE
it is a pretty well known rule here. DONT GO INTO THE OFFICE!!!!! mail in your reg230 form and wait. for the most part, the dmv office knows squat. the worse part is they will most likely try and make up a way to register your moped. it will probably be the incorrect way and set you back even more. if you just NEED to ride your moped while you wait, just ride it local (around your home). that way if you are pulled over you can explain to a cop that you repair mopeds and you are taking it on a test drive. of course again if you dont do anything stupid, you should be fine anyway. dont be dumb out there and get pulled over