I'm considering a "lite" .510, capable of "500 Whisper" subsonics, blackpowder, and moose loads in bear country. Anyone out there with advice?

I have been mulling something of this sort for a few months now. I talked to a gunsmith at Bowen Classic Arms and they saw no problem with either a rebore or rebarrel. Given that the brass is easier to come by in 50-140 form than 50-90 I have considered going with the full length 3-1/4 inch case. You can use XMP-5744 to get reduced loads I understand. The 50-90 will do anything that a 50 Alaskan will do, so its not really "lite", just lighter than a 500 Jeffery. It should make a great all-around hunting rig, just like the old 500 BPE.

Its ashame that the 50-90 is not more popular ... a friend of mine has one in a high wall and it is a delight to shoot,not to mention it has been very deadly on elk. I always wondered why ruger didnt set a 50-90 in a R #1. I just bought the #-1 in stainless 45-70, but have not given it a go. For myself I would like to try to have a #-1 built in 500 3" ill have to head up to Gary Reeders and have a talk.

I have assumed that the .50-90 2 1/2" in a strong action can be hotter than the 50 AK's 4,000 ft# as well as soft subsonic loads with up to 800gr. As I like to "manage" inventory, the variety of .510 bullets cast to VLD would make a long throat R.#1 fun and practical, along with a mid-power .50 bolt gun and .50 BMG in an 82-A1.
Strength of brass is a concern which I am learning is an advantage of the Starline 50 AK.
A friend told me of an Alaskan moose hunt with a black powder .50-110 2 1/2" Sharps where his companion hit a 1,000#+ bull through both shoulder blades at about 40 "muck staggers" dropping it like a bag of laundry.
I like the notion of a hunting rifle requiring tall tales of how close was the animal rather than laser range finders measuring clicks across valleys.
The 50 AK and 500 JAB/A-Square threads have some good data on throats and twist rates. I'll need all the recommendations I can find as all my experience is with .30 cals. to .22LR.