I have a snowlion -40dF bag from the 70's. Cost $500 back then.
Tried to sell it but nobody is interested.
Bought it way back when I contemplating some serious mountaineering that never happened but I have used it off and on over the years.
This was a top of the line bag that weighs 4# with 10" of loft.
4" bottom, 6" top with V baffles.
It is still in fairly decent shape but I never use it. Too freekin hot.
It has a 1.9oz shell so I would assume the down is probably 950+ loft.
I am thinking about shaking out the down to get an even 4" loft, whack it down the middle to come up with a 44x48 UQ.
I can use the rest of the down for other things or just sell it.
Alternatively I could buy some of the new SUL fabrics, and use this down to build a quilt from scratch.
That said I have worked with down years ago and find it an incredible PIA to deal with.