I’d say roll a bit of highs off the vibes, might be all it takes. One thing to bear in mind when playing older music in older styles… the recording technology of the day couldn’t capture anywhere near as much high end as modern digital recording can. You want to sound more like Lionel Hampton, start rolling off above 10kHz for a more vintage ‘vibe’!
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An arranger is just a tool. What matters is what you build with it..!