Urgent Storage Cupboard Door Problem

Hey all, I broke a cardinal rule, and waited to replace a door knob in a bathroom door. Well being the original knob, the mechanical parts wore out and i got locked out of the room with out the ability to properly remove the door. After a few hours of "Hard Work", not smart work, I ended up kicking in the door, and broke the jam. So now that i demolished any remnants of the old door, i went to get a new one to replace it. The rough opening was 31.5ish... (House Settling makes it imperfect) by 82ish. I got a 30X80 inch split jam door from HD but wasnt able to make it fit, so i returned it and got a 28X80. I was able to fit Jam "A", with the door on it to the rough opening, but had to cut about an inch and a half from the bottom of the frame due to the tile in the bathroom being higher than the conjoining carpet. I am having alot of trouble getting the jam to sit plumb and there is alot of space between the jam and the stud, so shimming is easier said than done... Any help would be greatly appreciated!

I'm trying to figure out if a solid core door would be too heavy for my type of door frame. My house's interior walls are basically a single sheet of 3/4" MDF. The doors are framed with 2x3's where the MDF is cut out. In the attached pic, that's not trim, it's the 2x3's. Currently the doors are cheap hollow core doors that of course barely do anything to block sound. While the rooms are never going to be close to sound proof because of the single-wall construction, it's obvious a majority of the sound is coming through the doors. The house was built in 1970 and I'm sure the doors aren't original. So, my question is: Will a solid core door be too heavy for this type of door frame? [ATTACH]75156[/ATTACH]