340 engine id

hey guys, anyone know what these numbers mean?
MH340R(?) (I think it's an R, the numbers are getting hard to see) then 38330001.
and the casting numbers on the side are 2780930-340-2
And the other side has 9 28 71. (Which I presume is the casting date?)

It also has R and a 3 on the passengers side above the bellhousing flange, but it's far to old to be an r3 block.