I can't advise regarding training other than to build up miles. 30lb eh? If you have mountains it will be interesting. For a 200mile ride I would suggest finding a sports drink and snacks that work for you. 200 is a long way from 60, especially on a heavy bike. Something like Heed energy drink and some carbo/protein bars will be necessary. Staying hydrated with a decent electrolyte balance will be a critical part of the ride. If you get badly dehydrated or run out of energy it will all be over. Your move to 60 miles was pretty quick but take care not to bite off more than you chew.