Greets fellow bonsai enthusiasts!

Need some advice, it's hard to find good reliable info just blindly searching the WWW and that's why I go here.

So my 13~17yo Colorado Blue Spruce died. Before I got it, it was in my parents' yard, and they were upset with its growth, always getting wind-swept and frost-bitten and not growing tall and "normal"/uniform/symmetrical so they dug it out and were about to burn it when I showed up, but I freaked and I took it instead. I had it outdoors in my yard for a year in a giant container and was quite happy with it.

Well this past fall was super wet and then the cold snap hit, and the tree turned into a giant Popsicle, needles gradually turned brown over winter and in the spring--as soon as I could act--it was too late; the roots were completely rotted.

I drilled larger drainage holes in the container and changed the soil to
a very ideal mix of my best ingredients, it's all set, except I have a
large dead spruce trunk in it.

I'm still hoping for a miracle that it might magically sprout some buds, but the realistic part of me tells me it's dead, completely gone... these are very unforgiving trees to do anything with, and I should know, I still have a couple other smaller ones from my parents' rejected selections, but they aren't as impressive as this one was.

Which slowly brings me to my point... a day ago I was just going to simply replace it with a large mature tree, but
looking at the prices it totally defeats the whole point of what I was
doing all along. I'm sure for a couple hundred you too can have a nice
already made bonsai! And then I got to thinking of all the work I put into this trunk while the tree was alive and it would be a shame to just get rid of it, maybe keep it as a lawn ornament at best.

One idea was to put a seedling in the container and just let it grow, but that would take a very very long time, and I have plenty of seedlings already.

Now, I am a bonsai amateur, but I've had this idea to merge a living tree with deadwood for quite a while... wind some young spindly tree such as a fast-growing elm (which grow like weeds here) around some chunk of wood. This dead spruce could be the perfect opportunity to actually do it.

ANYWAY, my question is what sort of evergreen would take best to merging with this surely-dead Colorado Blue Spruce trunk? If I carved a spirally channel up this spruce trunk and started training some kind of creeping juniper variety along that channel, would this work?

I need to ask because it would be a lot of effort to try this, and if I do it wrong and it fails, that's yet another big waste and tough lesson learned for me. However, with some good advice and pro-tips, I might pull this off and it would be a pretty impressive piece!