Repairing the input bearing is a pretty easy task.
Accelerating in any gear seems normal. It is when I let off the gas in gear that the noise is really "bad." So it could very well be the input bearing then.
Being non-mechanical or as some say, a parts replacer, I'm willing to hassle pulling the trans out, but I would have to check with a local trans shop for rebuild. One already said that there are no more old timers left that work manuals....Really??? I may search a bit for rebuilt or for a known good working one.