need help decoding engine/casting #

[sm73charger]

Can anyone help me decode some #s on my 360? My casting # isnt on the Casting page on here.
This raised # is on the left side of the block: 4006830-360-3 Im assuming this is the casting #
and this one is on the right side of the block: 4-26-78. Im assuming this is the casting date making the engine a 1978.
How can I tell if its a LA,RB,or B engine? How can I tell what it came out of? The guy I bought it from didnt know what it came out of cause he bought it from another guy who didnt know.
The only # I can see on the front side of the block under the head is 8W 360 6129 ? I dont know what that is? That
cant be the engine code, can it?
Any help would be great. thanks

 

[Deleted member 214]

All 360s are LA blocks. Easy way to tell - LA motors the distributor is in the back and is upright, B and RB engines have them in front and on an angle leanint towards the passenger fender.