Well, thank something for lazy Sundays!
After getting a little inspiration from SOME of the comments (thank you, constructive people), I applied sufficient interludes of cursing, sweating, filing, and grinding with the dremel, to create some ugly monstrosity that allows my existing trigger to fit. Started by filing back the entire section, before a few fitting tests showed I just needed a little shelf cut out for the trigger piece to move it.
This may be disappointing to those looking to shuffle through the loot pile, but it looks like I will have a functioning gun after all.
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