One thought, How does the distributor react differently to turning left vs any other situation? I have no doubt there is play in the shaft, but can't see how the car's motion would affect it.
I take apart LOTS of these. Most are in pretty bad shape. The pin holding the tach gear on usually needs to be drilled out. It is steel and it is tapered. drill from the smaller appearing hole after filing it flat and centerpunching it. 1/8" drill bit, use a TIN or cobalt bit, make very sure it is straight. If you don't get it straight, or try to hammer it out, you can easilly trash the shaft.Gary wrote the whole guide here. Replace with a roll pin.
http://www.311s.org/pmwiki-311/pmwiki.p ... yGaryBoone
The bushings for the EI units I make are definatly the right ID, may be right OD, I never needed to change one yet.
Distributor housing bushings, lower is Napa DP105 or Borg Warner DG 8, upper is Napa DP 107 or
Borg Warner DG10
If Spyder doesn't have what you need, I have a big pile of empty housings, I can send you a good one. Also, unless they are new, you should put in a new upper shaft, along with weights and springs, they do wear out, avail on ebay and elsewhere as a desmog or recurve kit.
Just a thought. Labor by the hour adds up quickly. If you are paying someone to rebuild your distributor, it may be more economical to buy an electronic distributor. The people who make them are listed in the Vendor section.