My friend in HS/College had a 70 340 Swinger that ran 12.4 and did not break loose the tires. He did have wide MT street tires and it hooked like crazy, almost snapping your neck.

I don't think there is anything majorly wrong with it, just feel it should do better. Once it warms up and I can get a compression test, fuel pressure gauge, and A/F on it, I guess I will know more.