I've just picked up a free mini K engine & gearbox.I've stripped the block back and am trying to work out the bore size.Rough measurement is 65.4mm.The pistons are marked +1.016.
Would I be right in thinking its 40 thou over.

Yes except your measurement is slightly under.
Stock bore is 64.59 so the bore should now measure about 65.6.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks.It was just a rough measurement as I was hoping the marking on the piston would give it.What I measured could have easily be 65.6.
The bore, rings and bearings (apart from 1 cam bearing) all look in good condition not that I would be reusing them.I don't think this engine has seen a lot of use since its last rebore.
It was part of a project that didn't go ahead.I also got the doors, bonnett ,grill and instrument cluster.
A quick look at the gear box looks good too.