Once the taildragger training has ensured your basic stick and especially rudder skills are up to date, forget an instrument rating if you are after enhanced flying skills. An IR will only exercise your flying skills in a narrow part of the flight envelope (albeit to a high degree in that narrow band), and will need a lot of practice to keep valid. And will you really use it enough to justify that?
No, as Foxmoth says, try aeros. Absolutely nothing else will teach you how an aeroplane really flies, and why it sometimes ceases to fly. Across the entire envelope.
But there's no point doing aeros until you are sure you have the basics mastered.