You can carefully drill into the heatsink so the heat break tube sits higher. It seems to be OK leaving just a tiny gap between the collar on the block and the heatsink. I also chamfered the hole in the top of the heatsink because the corners were sharp compared to stock.
In the mean time a 0.6mm nozzle has been printing PLA and PETG at 35mm^3/s. Initially it would do PLA flow tests at 35mm^3/s and 225C but the heater could not maintain 235C and would error out. After filing down the nozzle it seemed better possibly because the nozzle didn’t poke out of the silicone sock as much. I think I did a PLA flow test OK at 230C and I have been printing parts in PETG at 240C, but, for parts the average flow rate would be less than 35mm^3/s.
Well thanks but this is is somehow have already be mentioned elsewhere :
EDIT: anyway the only good solution IMHO would be to have a thread length that match standar nozzles, cutting heatsink, using spacers to make contact, all are workarounds