You don't say how many miles the pistons had done (if you know, that is). If 'not many' I wonder if the person who bored the cylinders to +80 had the pistons to hand when doing it?
JPs need a generous skirt clearance. It looks to me that it hasn't been provided, unless some other horror show has caused the damage.
When I had some barrels resleeved for another make, and used JPs supplied by the same people, the skirt clearance provided was nigh on 6 thou, on a 72.5mm bore (which is near as dammit where you are at +80 on an 'A'). They have done 15000 miles without any problems and with what I regard as 'normal' modest oil consumption for an engine of the era.
On my own A, newly fitted with a pair of IMDs during lockdown, I have a similar minimum clearance of 5thou+. Too early to say how good they'll be, but not a whiff of smoke from the very first start-up, and spins very nicely.
Personally, I prefer to go a bit 'large' as a matter of course . . . makes no real odds to the lifetime of engines that aren't being used as daily essential transport.
Looking also at Chaterlea's wise comments in the other live thread on here at the moment,'Big Jim's decoke . . .' it just goes to show how important it is that the bottom half be put together properly too. If 5000 miles is all it took to cause the top end trouble there, the job certainly wasn't a good one. Sadly, jobs that 'aren't a good one' are not rare!