They are standard A14-size valves: 37mm & 30mm. A12s have 35 & 29.

I don't know what an H89 is, but this head is like an A14 head except:
* peanut shaped chamber (not heart shaped)
* Shrouded port. The valve guide is half hidden for high swirl.
* These are small ovals, not the regular size oval
A12A Oval: 28x30 mm
A14 Oval: 28x34
GX Oval: 30x36

shrouded port:

Like the new GM Gen III V8.

Soooo..
are we saying Peanut chambers and shrouded valves is a good thing???

I swapped a later model round port onto an A12, and it made a huge differance, I didn't investigate the differences in the head though, (I think i drilled the oil gallery into it though...)..

From memory some of these late heads have extra ports behind the exhaust valves to form part of the EGR [Exhaust Gas Recirculation] circuit. H89 does sound familiar.

This head looks pretty much like the head from my US spec A15. I can check the numbers tonight. The shrouded intakes are good for emissions and gas mileage but not any help for performance.

[Edit:]
Checked the numbers on the A15 head in my collection. The numbers are H95 708. This head does not have the air injection ports in the exhaust valve pockets. The air injection was done via the exhaust manifold using the pulsing of the exhaust to draw air through stainless steel pipes that were connected to reed valves in the air cleaner can.

This head was used on all 1981-1982 engine in USA (A12A, A14 and A15). The design was reduced emissions, increased fuel economy.

For details see H95 Head