30deg initial timing!?!?!!

[ol'blu72]

I finally have gotten back in my blazer after only driving it like 3 times in the last 2 years and decided to do some tuning. I set my timing "seat of the pants style" by driving it around town and making adjustments in random parking lots to get the best throttle response and power for all driving conditions. I was the best time I have had in a while. I got her dialed in and she runs great and pulls strong.
So i got her home and decided to check where I was at with my light and to my surprise she is sitting at nearly 30deg initial! I did some revving and mechanical advance is 30deg all in at 3500. This is just strange to me and I am thinking something is wrong. What do you experts think?

Details: Newly rebuilt (1000mi ish) 350 in a 72 blazer. Vortec heads, summit HEI dizzy, the mildest comp xtreme energy cam they got (probably similar to a RV cam). 350 tranny, 3.73 gears.