Those are a set of 346’s.
2.14/1.81

I did work on a set of the repro 518-M’s last year though.

I’ve never had a set of original 518’s in my shop, so I can’t say how similar they are to the -M versions.
But I can tell you this........ both the intake and exhaust ports on the 518-M’s are shaped nothing like the early 286 heads.