V8 to /6 vacuum advance

Depends on the distributor (yours and the V8 ). The canisters all look pretty much the same, but the arm that hooks onto the breaker plate can be different -- different curve, different bend (up and down), different end (some have a peg, some have a hole).

But I don't know about this whole approach -- the vacuum advance isn't going to kick in right off idle. Did you set the timing with the vacuum advance disconnected and the hose plugged?