timing problem

so i've got an 85 model 318 with with 308 heads on it a edelbrock performer intake,Carter AFB, 904 Auto,spitfire headers, and 2.5" dual exhaust, and 2.23 rear gears stock roller cam in a 66 barracuda. I went to check the timing today to see if i could get a bit more pep out of the car and noticed that the mechanical advance on the distributor was only giving me 17* advance at 2500 RPM. Which combined with the 2* initial brought me to 19* total timing. I've heard that these motor like 30-35* total timing so i went back and set my initial to 15* and drove the car and it's not pinging under load and cranks just fine. I'm reading 24 inches vacuum at idle in gear, which sounds like too much vacuum. So I'm beginning to think that i have something wrong because 15* initial. timing seems like alot. I rechecked my timing mark on my balancer and it is correct and used 2 different timing lights and vacuum guages thinking that i had a faulty tool. So my question is
1) what kind of vacuum should i be reading in gear with a stock cam
2) am i running too much initial timing
3) where can i get the springs to recurve the distrubitor to get more mechanical advance if necessary