I just love to read these "just one gun threads"!!!! I think that you left something out, just what (make/model/year) is that "very good 30-06" that you wrote so fondly about??? For the game you want to hunt for, elk/moose, I think that the 30-06 is more than an adequate cartridge for both species. My absolute, go to gun is a Remington 700 ADL <<----nothing fancy, in 30-06. I bought this rifle for my father back in 1969, it has a Leupold VariX IIII, 2.5-8 scope set into Weaver rings and bases. I glass bedded the rifle and put a Pachmyr Decelerator recoil pad on it like thirty-years ago. That's it, nothing fancy!!! I had my first black bear hunt come up out of now where ten year ago. The story goes that while at a family barbecue, it went from, "Boy I'm gonna go on a bear hunt some day", to, "I'm not going to be sitting in a rocking chair of a nursing home and saying that I wish I had gone on that bear hunt!!!" I made the call from the barbecue party to the outfitter and was packing to go on a bear hunt in three weeks. I had rifles, but knew that the Remington 700 in "06" was (1) a reliable rifle, that (2) I knew had enough knock-down to get the job done, (3) I was very familiar with the rifle and could shoot it well. I hadn't shot that rifle in many, many years, but....I knew the rifle and always considered it to be the "go-to-rifle" for such an occasion!!! I developed a load with some 180gr Barnes TSX and was ready to go. Since that time the rifle has been sitting in the safe, and still is the go to rifle that never gets messed with or changed in any way. It probably will never get used again in its capacity as the go to rifle again, but....it's still the go to rifle!!!
This could turn into a dissertation quite easily. You did not mention if you are a reloader or not? If you are a reloader the options are immeasurable for you. You can go to all of the new, fastest, greatest, hardest hitting, two-mile one shot T Rex destroyer designer cartridges out there, but no matter what in my the 30-06 is still a tough one to beat. Yup you can go to those, but these designer cartridges come at a price to include price $$$, availability/access to ammunition or components like brass (@$3 a pop) and with a whole lot of recoil to name but a few!! Also (for me) as far age goes, seventy-six times around the sun, what I have found is that along with those orbits comes a bit more sensitivity to recoil than in previous years. So...those magnums are not so much fun to shoot as they were a number of years ago. A few years back I purchased a 338 WinMag because I'd read so much about how good they were. Five rounds through that rifle and I was done, never shot it again!!! After that range time I had to make a visit to the dentist to see if my back molars needed to be glued back into place.
My thoughts are that if you have a rifle that you are fond of, as in "I HAVE a VERY good 30-06", then....why not build yourself another VERY good "custom" 30-06 using that same platform. When it comes to hunting rifles there's nothing more exciting than to build a hunting rifle based upon what you have decided to build, the components you plan to use to do that build and who is going to build that rifle for you. Although the go-to-rifle is a Remington 700ADL, I am fond of Ruger 77s and have built a number of semi-custom rifles in various cartridges. By semi-custom I mean using the Ruger 77 platform, blueprinting the action, rebarrel (contoured Lilja 26 inch 1:10 barrel), trigger job, free-float and glass bed and pillar bed the stock; and it is in 30-06. I could have gone with a new glass stock of some kind, however I prefer the vintage looks of the existing stock; see attachment. With the blueprinted receiver and rebarrel the gun shoots cloverleafs at 100 yards, and presently far better than I can shoot it. As for those 500+ yard shots, I am not so sure of how realistic they are gong to be for me at this age, and perhaps how realistic they will be for many hunters who are reading articles in this forum if they are honest with themselves? I was going to end this with, "This is just my .02c worth, probably more accurate with my $200.00 worth. I'd like to suggest one more thing, "Remember this isn't a dress rehearsal, if you want it get it and have no regrets!!!!" Life should be the only word for a reason to purchase a new rifle. Good luck with whatever you decide upon getting for a new rifle.