For sure. My conversion plan NEVER demands that the original wiring be removed or cut. Hell, those turn signal circuits are great for powering external gauges and lights. Flip the turn switch and LIGHTS!
That is exactly what I did to mine. When I got it the battery was removed and the wiring was tied up. Luckily they didn't cut any of the wires. I just reinstalled the battery and got a stock rectifier/regulator. I put the turn signals back on and now all the lights are working. The headlight is bright and does not dim when I step on the brake.