Return of Royalty is more of a coffee table book pics of sheep. Safari Press has books by Jack O'Conner that are informative. I just purchased his "Hunting on Three Continents" for which the first volume discusses sheep hunting. Another book of sheep hunting is by Batten. Look up the author online. There are many book offerings at Safari Press.
Now, after having suggested these I will say that sheep hunting in the lower 48 is very pricey and difficult to draw a tag. To hunt in B.C. is again pricey but very do able. You might want to consider an unlimited sheep hunt in the lower 48. But, there is no guarantee drawing a tag or for that matter even getting a chance to take a bighorn. Desert bighorns can be hunted in Mexico, but pricey. Dearest bighorns can be hunted in NM and Arizona by drawing a tag but tough to draw.
I would recommend an Aoudad hunt to begin with. There are many outfitters in west TX. Also, there are many exotic sheep to hunt in TX and in Hawaii. Attempting to talk my wife into Hawaii for our 50TH and I could hunt sheep while she lays on the beach. Time will tell.
There are Ibex in the Florida mountains in New Mexico, draw only. Tough hunt, very handsome animals. There over the counter Aoudad tags in SE New Mexico. Very low percentage hunt. But, a sheep hunt none the less.
Do not know what you desire in a way of a hunt. Albeit there are many ways and means to go about what you want in a sheep hunt.
Here is a true adventure suggestion. Consider a hunt in New Zealand for Red Stag, Himalayan Tahr, Arapawa sheep, Fallow deer and more. We will be returning to NZ for our second hunting trip this coming a June 2020. This is a true grand adventure. Something to provide great memories, great trophies and scenery that has little comparison.
There are ways to have great hunts. Plan and dream. If I can be of help PM me. MTG