I am helping a friend of mine with his 1934 Airflow street rod.It has a 1985 318 out of a b300 van.We are using a 1975 318 dist.The distributor has worn bushings.Can you buy replacement bushing or should we just buy a rebuilt dist?The engine was rebuilt with a perf rv Mopar cam with a early Mopar dual plane intake and 500 eled carb.Any idea of a good base line for ignition timing.We are also using the #302 heads from the 1985 engine.How do you block off the lower ports for the air injection so we can use regular headers? Thanks for any help.

You could just get another dist from a wrecker. Put it in at 36 degrees full advance without the vacuum advance hooked up. You can plug the smog holes with correctly sized rivets.

I'd get a JY elec dist, take it apart, clean it w solvent, blow it dry, lube it, reassemble wo the heavy spring w the long loop and add another one in it's place (not sure whats available & set the initial @ 10. That'd get you started cheaply.

I don't know if you have one in your area but autozone carries them for $34.99 with exchange.

you can also plug the air injection holes by taping the holes with 1/4" 20 and put a set screw or bolt and cut off the head in the hole.

Or I MIG welded the holes up. Cut the tubes off flush and cleaned them up real good and welded them shut and bolted them back on.

not sure about the bushings, but Autozone has rebuilt dist for $40.
Just about anything will work to plug the air injection ports. Some headers have metal plugs you can just pound into the holes.