Valvetrain identity

The rockers look to be factory 273 adjustable rockers. The valve springs aren't double springs, the outside is a spring, the inside is a damper.

Those springs "look" like the comp 901-16 springs that come with a lot of there mid range cams.

If I'm reading the number right the heads look like: 2531894 340 1968-70 2.02 1.60

I'm not sure if the 340 heads came with those style rockers or not. Someone else will have to verify that.