Before you send your pistol in, Id check out Bruce Gray's Gray Guns website. He's a top rated pistol-smith & instructor. He's very well known for SIG models & the HK pistols.
Another choice is TJ's custom gunworks in Culver City CA(LA area).
He's been in business for decades & does many custom/duty/exotic work on guns. SIG Sauers are one of his staples.
Note; I've heard & read in the past that he's not the easiest shop or person to deal with.
Keep that in mind before you spend any $$$ on custom SIG work.
Both of these SIG Sauer pistolsmiths might be delayed too due to the extreme demand(s) for the shop work.
Clyde