there are, or were, two stampings on the block that would designate year.
the two letter engine code for a 1970 Electra should have been "SF" and indicates the 370hp variant, which was the highest OEM rating Buick ever had in a production vehicle.
the EIN ( short variant of the VIN ) should be something like "4 0 H xxxxxx". 4 indicating the Buick division, 0 indicating the 1970 model year of production, H indicating the Flint MI plant ( there are other plants but Flint is primary ) and the last 6 digits matching the VIN of the original car it was installed in.
your engine should have Buick Red paint and the valve covers should have 5 bolts each. 6 bolt valve covers indicate someone swapped in a Buick 350.
The way to crush the bourgeoisie is to grind them between the millstones of taxation and inflation.
Government schooling is about "the perfect organization of the hive."
H.H. Goddard, Human Efficiency (1920)