Alright, it ain't my best run of the game, but here's a save file with all story missions complete, and a bonus one with The Exchange left for you guys to play. I left most of the side missions for you to muck around with. Also, as some storyline missions can be skipped (i.e. Joey's) I made sure that each and every mission has been passed for 100% completion.
Simply paste the included save files to your GTA3 User Files folder in My Documents.
Feel free to redistribute or play around with them saves. Credits are encouraged, but I won't mind if you don't give me one for this.