Needed parts:

1.  Steel control arm

• Paragon Products - Steel control arms

2.  Front of rear caster block

• Paragon Products - Caster block

3.  Front of rear bushing

• Paragon Products - Weltmeister Front of rear bushing (Weltmeister bushing is recommended over the stock rubber and it is cheaper.)

4.  Front of front bushing

• Paragon Products - Front of front rubber bushing

• You may want to switch to Weltmesiter or Delrin(Racer’s edge) bushings here, but the cost difference is pretty significant.

5.  Bolt in ball joint and bolts and nuts associated with them.

• Paragon Products - Ball Joint
• Paragon Products - Ball joint hardware kit

6a.     Sway bar end links (85.5-86 Drop links are NOT the same) and bolts and nuts associated with them.

• Part #: 5 in diagram: Paragon Products - Sway bar bushing clamp(end link)
• You will need both left and right.

• Part #: 6 & 7 in diagram for bolts and nuts:  Paragon Products - Sway bar hardware
• You will need 4 of each.

6b.     If you do not want to get new end links, you can drill a hole in the steel control arm to accommodate your current sway bar drop links.  (Not advised)

7.  Sway bar end link bushings.  If you plan on running a sway bar larger than 23mm then you will need to bore out the bushing to the appropriate size for your sway bar.

• Part #: 2 in diagram: Paragon Products - sway bar end bushing

8.  If you plan on running a sway bar larger than 24mm, you will need to use the 87+ center clips and appropriate size center bushing.  The 86 and earlier center clips will not work as they are too small.

• Part #: 5 in diagram (use 87-): Paragon Products - Part #: PP944.343.731.02

That should be everything needed to make your conversion to steel control arms.  Porsche put out a TSB about 85.5-86 aluminum control arms not being used for serious competition, which is why it is recommended to switch to steel control arms.  Not to mention they are easier to replace and extremely cheap if you ever have to replace the control arm, bushings, or ball joints.
Good luck out there!