CJH, thanks for the reply.
The engine is in situ so I guess you need to wiggle the push rods during reassembly to seat them properly. Previously I turned the engine over with a spanner and it seemed OK, perhaps I didn't do sufficient revolutions to check all the valves.
The head is now off and I can see there is very slight marking on the piston heads where the inlet valves have just touched, but otherwise no signs of damage.
I've straightened the push rods (can't see any available on the usual supplier's sites, they seem to be made to order)
Here are some photos. Not sure what to do now

I don't want to do any more damage.
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