No the vac advance port hits the motor mount,,
I'm not familiar with your year truck. But I believe your Vac advance should not be turning or hitting anything when your adjusting your distributor.
On my year truck for initial timing you set the octane sensor at 0 and Tighten the bolt down
HERE then if you need to adjust the distributor your loosen the collar
HERE and turn the distributor to adjust.(this is how I advanced my distributor for the pertronix system on my truck)
others will soon correct me If I have this wrong.
can you post a pic of your set up?