Welcome to the site for starters

It sounds like if its been laid up for a while the release bearing might of got stuck or theres no oil in the box and what your hearing is the gears eating them selves

Id try another box in there you can pick up a 3i box up off ebay pretty cheap then just change your clutch and release bearing whilst the box is off that way you know your eleminating all the things it could be and your not going to have to do it again in a hurry.

mark.

Ps get some piccies up of the car in question