70" 340 vs 72" 340 specs please

I've had some strong 318 and some dog 340 , a good strong (stock) 318 will keep up with a dog 72-73 340 , it happens . I've also had 2 70 318 Darts with 318 and 1 was 2 seconds faster in the 1/4 mile straight from the factory . Machining was really hit or miss back then , had a new 440 tnt seize up on me after 1 week of driving !