Thanks. That's good enough for me.

@@ -11,0 +12,3 @@
+<re_pri>news2</re_pri>
+<re_pri>nf39</re_pri>
+<re_pri>spec2</re_pri>
@@ -15,3 +17,0 @@
-<re_pri>news2</re_pri>
-<re_pri>nf39</re_pri>
-<re_pri>spec2</re_pri>

screenshot of 日本語発音アクセント辞典 entry for 谷底:
https://files.catbox.moe/kbibzq.png

it puts たにぞこ first

https://dictionary.sanseido-publ.co.jp/column/sankok99
https://furigana.info/w/谷底

たにそこ leads たにぞこ by 87.5% to 12.5% in Aozora Bunko (but most of those examples are pretty old).
The above Sanseido article says that たにそこ is the original reading but most people now pronounce it たにぞこ ("現代の大勢も、まあ「たにぞこ」でしょう").
I have no reason to doubt that, but could it be that たにそこ is still considered more "correct" (e.g. in technical contexts)? Which reading does 日本語発音アクセント辞典 list first? I don't have access to that resource.

スーパー大辞林
NHK 日本語発音アクセント辞典
研究社 新英和・和英中辞典
精選版 日本国語大辞典
明鏡国語辞典

That link pulls up all the instances of 谷底 in youtube subtitles. Almost everyone says たにぞこ

(goes without saying, but ignore unrelated results such as 谷底平野, subtitles for videos in other languages, people who uploaded inaccurate automatically generated subtitles, etc)

I hear it as たにぞこ in tv shows as well, but I don't have refs to provide

@@ -9,0 +10,3 @@
+<r_ele>
+<reb>たにぞこ</reb>
+</r_ele>

wisdom, daijr, shinemikai

The refs only say たにそこ. And I don't see where the alternative pronunciation is in the ref you gave.

@@ -10,3 +9,0 @@
-<r_ele>
-<reb>たにぞこ</reb>
-</r_ele>