While @Smithy has given you the best advice, if you elect to attempt this, you will need specific nozzles made for the UM3/S3/S5 print core.  I bought ones made by MicroSwiss.  The rest of the caveats are in my TL:DR post a bit higher in the thread.    My print core is working well with no leaks and I find the print quality pretty much indistinguishable from my unaltered OEM cores, however the  plastic frame is a significant factor, heat seems to deform it over a long period, such that