Partsplaceinc.com ,google vw parts place .
That's where i used to buy parts for mine when I had it . I never could find a 1.6 idi specific forum I would just google search . A lot of guys send their pumps out to Giles and have him build them . Nets a decent jump In hp .
I would buy a timing belt tool set . Vw is big on some funky special tools , you can get by without one. It's good to have the right stuff though. Keep an eye on your head gasket . Fairly common to go out , also change your timing belt if your even skeptical on how old it might be. These are interference motors and if the belt goes it will destroy itself. Keep an eye out for fuel system leaks as well another common thing . Mine was a 4 speed and i didn't like the rpms at 75mph commuting . The mk2 platforms had 5speeds though . Straight forward swap.
I was getting 50 mpg regularly on mine !
Take care of it and it'll take care of you .