First off, welcome to the Forum Paul. I'm like you in that I have many started but few finished. When I see a finished model, my eyes are always drawn to visible mold lines and parts seem lines. Call me crazy. LOL Something like an out of box build is finished at the comfort level of the builder, so may or may not be important. The completed model that do puzzle me are the ones that are immaculate ... paint, fit, finish, details ... however no seem/mold lines have been removed from radiators, engine blocks, transmissions, exhaust systems and so on. If the builder went to theses lengths to achieve realism, why leave behind blemishes that give the finished model a toy-like appearance? I know, I know, this has been covered a million times before. And of course, this is my take on things.
The .5 needle/nozzle from an Iwata Revolution series is cross referenced as the optional set for the Iwata HP-CS. I have done this to my HP-CS, and it is much more forgiving in terms of paint viscosity. You can download the parts/users manual for an Iwata Revolution. This will give you the Iwata part numbers for the needle, nozzle and nozzle cap. Hope this helps. I just found the information for the 0.5 needle. The Iwata part number is I 617 1