I rebuilt an MS460 and used a Farmertec handle, brake handle, and fuel tank/handle along with a Meteor piston and cylinder. I run a 28" Tsumura lightweight 3/8" pitch .050" gauge bar on it and Oregon full comp EXL chain and this is my biggest saw. It runs like a beast and I have had zero issues with it. I don't use it professionally, just really into firewood (40+ cords stacked in holz hausen formation).
Quality felt great and for $60 it includes the fuel line, the vent, the trigger assembly and cover, wiring harness, switch, and the bushing in the front. The oem one is $200 and comes with the flippy fuel cap and nothing else.
But before you go buy anything, have you checked/replaced the fuel tank vent? I had one leak on my 034 Super and replaced just the vent. I'd fill the tank up with fuel and wipe it nice and clean and then tilt the saw and carefully look for a leak. Can you take a picture of where it's leaking?
https://www.hlsproparts.com/product-p/h58460.htm