Thanks for answering my question.I had one done once, about 9 years ago. It is a 110 LE with a 20" 7mm Rem mag, Savage bull barrel. They offered my choice of stock and that is about it other than caliber and barrel contour or length. More of a special order shop than a custom shop.
They don't do trigger work or action truing or any other accurizing options, or at least they didn't then.
Took around 8 weeks to get rifle from time of order to me. No difference in cost than a standard 110 LE at the time.
Savage is quick to distance itself from the term “custom,” as its service uses standard production parts to assemble the guns, and they receive no extra fine-tuning above and beyond what the main line firearms are subject to.