Just get some barends. Most bullhorns are roadbike diameter, a little bigger than mtb, so sometimes tough to get shifters and brakes onto.
Or go vintage and get Brahma Bars, Scott at-2 or 3. You'd probably have to get another stem for those bars - 25.4mm clamp.
I like to sit and spin all the way til close to the top of a road grind. Once near the top up shift twice stand up then power over the top, put her in the big ring.
You can switch back and forth to just practice shifting. Pedal light while shifting.