I have read that the actions on these are supposed to be extremely simple and sturdy, with outstanding metallurgy, yet have never seen one used as a donor on a what would pass for a tricked out "24HCF approved" hunting rifle. They seem more relegated to beater truck gun assignments.
Would fixing one up be akin to making a silk purse out of a sow's ear?
There are collected as desirable piece of history, so; it would be a bad idea to waste one for a sporter. It has been done in the past, and as you say the action is strong enough for a good enough result.
These guns are generally on the crude and ugly side. Some, last ditch, far worse than others. None pretty. The earlier 38's are better finished. The early 99's are kinds cool in an ugly way with mono pods and anti aircraft sights. Ugly is how they look and it must be an acquired taste as prices have skyrocketed. Far beyond the Covid/Biden increase we see across the board. I mean big time appreciated. It would be a waste to start with one of these to build a project. They are no longer beaters.
The OP's pictures are not very good. I dont see what the over all look of the gun is! Could be a rare model. I dont see anything special in the few closeup views provided. Probably a refinished stock, which hurts the value. Not just refinish but; heavily sanded. I thinki? Sanded stock, ground mum, unknown model due to limited photos.