Engine willbe fine with vacuum advance when using a mechanical advance shaped like this.
View attachment 1716088262
or these
View attachment 1716088261
And with no vacuum advance it will be OK with a fast curve like this.
View attachment 1716088263
Can't mix the two.
Below 3000 rpm or so will result in too much lead time at light and part throttle.
It will manifest as flat spots on the throttle response and /or pinging under moderate throttle once the engine is fully heat soaked.