Williams does great work and can even add a set trigger to your HK if you want more than their standard trigger work. I have had a half dozen rifles done by them and they do stand by their work.
You have a HK made PSG1 rifle just to be clear? The trigger pack in these rifles ( PSG1s ) are suppose to be adjustable but then the trigger pack in my PTR-91F is adjustable too. Both of these Smiths mentioned are the go to guys in HK rifle land for trigger work. I'd make a phone call to each and have a chat about what can be done. A new PSG1 trigger pack is $900 at HK parts and the trigger group complete is $ 1995, HK still hates us.
Jump62
aka Paul
The trigger in the PSG1 is different than your garden verity G-3, the rifle was built from the ground up as sniper rifle. This is what the trigger pack looks like https://www.hkparts.net/shop/pc/PSG-1-Trigger-Pack-Assembly-German-37p907.htm most G-3 trigger packs don't go for $900 even at HK prices.
Jump62
akaPaul
I like my 91 just like it is, built from a G3 kit on a Gear Logo receiver. I'm not much of a sniper though, more of a shoot them and kill them closer up. lol
Check RobertG too, he has a lot of HK parts and is my go to guy for them. Known Robert for a long time now and he is a good guy. I built my 91 and I don't do this stuff anymore due to health issues so I guess beyond parts, I can't help much.