Timing a "unknown camed" engine....

I used the OEM Ford springs..( 68 Mustang 302 Distributor )The car runs good...but I have to verify the numbers ( advance aso ) the next days... will keep you informed
The timing @ idle is now 17 deg. BTDC 18 deg. advance
and around 15 deg from the vacuum canister... so far so nice.... but when I drive steady 50 mph .. ( more or less)
I think I have some "noise " comin from the engine...If I go off the accelerator the sound is gone...also if I accelerate ..
Perhaps I need to reduce the Vacuum advance a little more...??

Greetings Juergen