FE original machined combustion chamber heads

[Harris Speedster]

Guys,
I have a set of virgin FE heads that I am trying to identify, Coopers 45 year collection.
The part numbers have been ground off, may many moons ago .
The heads definitely have the smooth machined chambers, like High riser heads.
Chamber is a horse shoe shape.
Took some sodium filled valves from some 427 M/R heads, they dropped in, but stand about 1/16th of an inch above the stock seat ?

Any idea's?
I checked out early 406 and 427 low riser>> which low riser was a made up name, according to some sites I researched.
Any body know what they are?
John

[427heaven]

John-  They are probably 58,59, 60 Heads. Great early performance heads with clover leaf combustion chambers. They wake up lethargic low compression FE'S

[Bill]

Pics posted for JH