my first suggestion would be bushes and a quick rack.
suspension wise GAZ is good for street. they are user friendly with the external adjusters. i run bilsteins in my 2 door and have found them to be excellent though a bit more pricey and a bit more involved to set them up.
you can get rear leafs made up with anti rebound leaf that will help stop tramp. they are a direct replacement too.
you can get tube kits to make your own front coilovers which are pretty good. otherwise a decent set of springs will do.
front brakes can get a M16 caliper spacer kit to run vented discs. pretty simple instillation.
LSD is always nice or you can lay some rods into the diff. axles will be the weak point though.
best option though is a decent set of rubber.
of course its all down to budget but there are some pretty cost effective mods you can do to that will help alot