Help identifying these LA 360 Heads.

Hey there,
First post. Long reader.
Buying my first classic--73 Duster with LA360 swapped.

First, ignore the butcher paint job on this block. Not my fault!
Second, I cant identify these heads-- I checked between the spark plugs and there's only a '31' on the drivers side and a '27' on the passenger side. No X, J, U, W... etc...

Can someone figure out what they are? Cant open them up quite yet.

Thank you,
Ben

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