72 360 v8 with 340 J heads?

[DMZ73]

 
This is silly, and I apologize if this has been covered repeatedly.
What are the benefits of using the 360 blocks with 340 j heads?
Are thee 360 j heads?
Since I can't read the head identification, is there a way to tell?

Best,
Dan

[Ck[FIN]]

I remember that the 360 j-heads used 1.88" intake valves and 340 heads used 2.02" intake valves. Everything else was the same. 

[Chryco Psycho]

the J head was used from 70-73 & had both 2.02 & 1.88 intake valves depending on the year
 as CK said really very little benefit they were not significantly different from other 360 heads with 2.02 valves installed
 the best bang for the $$ I have found is the later  308 castings ported