when doing my custom pistons for my hillman Imp gt and later triumph herald both small L4 engines, I was recommended not to go below 2.25mm for the intakes and 3mm for exhaust valves especially going over 6500rpm yet stuffed up with my one tonner engine rebuild for rushing the build since it was my daily.

I would say you are not safe with this clearance and need more as rods stretch quite abit on missed gear changes and revving high with no load. During the dyno tuning of my 355 stroker 25 years back the tuner was able to hear the valves hitting the pistons which was just audible at 7000rpm and was a lot more work taking the pistons out, new valves and re assembly than where you are at now.
I later had a rod let go which always made me wonder if that one slug with the most damage should have been a reason to change the rod. Rods take good compression force but being stock ones with 300K Kms factory Hoes not checked for cracks it ended up ruining the crank and then licked my wounds and went the extra steps for my 383 and never looked back.