Yes they are F3 heads.

The casting for both heads is the same as stock. The plug position is also the same as OE.

The internals are different though having a tighter squish but less compression that the standard heads. They also say RR on the casting the same as the SP heads.

As Andy says the rear head on the front was a MC28 HRC idea.

The F3 one's don't come up very much now so I machine stock ones now as and when I need more. Front heads are also cheap which is a good thing as no one wants them!
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If I have to take the carbs off once more...