LA head casting ID help.

Thanks to all.
Does anyone know what the "B" in the casting number for?
Could this head have come on a 1973 340 car although it was cast in 1972?
Does the "360" on the head stand for a 360 head?
In looking at various post's would this be a 360 head as opposed to a 340 head?
"3418915 – 1970-1972, 360 LA-series small-block, 1.88/1.60 valves, 65cc-73cc"
"3418915 – 1971-1972, 340 LA-series small-block, 1.88/1.60 valves"
Would a 340 head say 340?
Happy Mopar :)
Arron