I was going to improve my old namco arcade stick, in the end i replaced the buttons with semitsu PS-15 (i discarded the PCB in favor of a "supergun" custom cabling).
about the stick i didn't want to buy another one because the HORI one was precise enough (and it mount omron switches) but the resistance was simply ridiculous so I opted for a spring replacement instead of the entire beast i with a semitsu LS32 one (LS32-SP is the part name) that costs 1 dollar.
The only thing that could now tell the difference between a real sanwa/semitsu is the missing of an octagonal restrictor.
Hope my advice is helpful to the ones that are going to modify their namcos