Base timing depends on alot of things. Yes, an engine can run well set at 0 base timing because the distributor is set up that way. For example;
You have a stock smogger 305 ( non CCC ) and the specs call for the base timing to be set at 0. Man that seems low doesn't it? But dig a little deeper. The distributor give alot of vacuum advance ( lets say 20* ) and you have it connected to manifold vacuum ( meaning the vacuum is 'on' at idle ). That means at idle, you'll have 20* total timing ( 0 base + 20* vacuum ) which allows your small cammed engine to purr like a kitten.
Now lets look at total timing. Most engines would run best somewhere around 36* total timing. Total timing is your base timing ( without vacuum advance factored ) + what the distributor gives you. The timing a distributor gives you ( called centrifical advance ) is COMPLETELY independant of what the vacuum advance gives. A distributor is designed to give you more timing advance as the RPM's rise untill a certain point where it doesn't give you any more. You need to know how much the distributor is giving you. If you have your base timing set at only 0. then you'd need the distributor to give you 36* to achieve the 36* total you'd want ( 0 base + 36* from the distributor ). Now if you're base timing was set to 12*, then you'd need a distributor that gives you 24* if you wanted to achieve your goal of 36* ( 12* base + 24* from distributor ).
Distributors are also shown as showing where the RPM it will give you ALL of it's advance in by. For example, a distributor would be shown as being '24* @ 3000 RPM'. That means it will give you 24* maximum advance at 3000 RPM's and higher. It would give you less at lesser RPM. It should give you no advance at idle.
So as you can see, you really gotta know exactly what you have and set it all up correctly if you want best idle, performance, and milage. If you want more indepth info, just Google this and you'll get more info than you'll ever need.
P.S. My engine has 16* base timing and my distributor gives me 20* centrifical advance at 3000 RPM and above. My vacuum advance gives me a max of 14* of vacuum. So at idle, my engine is at 30* ( 16* base + the full 14* of vacuum advance + 0 from centrifical because I'm not at a high enough RPM for it to kick in yet ). The absolute maximum timing my engine could ever see would be 56* at 3000 RPM or higher and during light part throttle cruise where my vacuum advance is able to give me my full 14* of vacuum advance ( 16* base + 20* of centrifical + 14* vacuum advance = 56* ).
i'll take it on chin, i aint going back to fix nuthin...im not disagreeing because the vin says it all but when i buy parts (an oil pressure sending unit) they ask engine code Y or 9 and the Y parts didnt look anything like the 9 part which was an exact match. i think i would've been happier if you BSed me an made me believe i had the H/O lol but all that aside, what is CCC? the "cops cant catch" package? i definately dont have that if thats the case. this guy before me changed the color from green to black so he painted everything you can see, no stickers in the engine compartment, painted over on the doors and trunk...well ill have to check the trunk but im pretty sure they're painted too...not 100% tho 
so what would 0 degrees be at on the tab? the tube? did you get a chance to check out the pic? today i set it to the 3rd outer point from the tube and its running decent but i still think shes off by a bit. i was thinkink i might try it on the inside point above and then below where its at and see what each of those is like.
