new and had a few questions about a rotary im going to purchase

[JesseV209]

Heres a tattoo I've done. outlined with a coil machine and used a stealth rotary for the shading and dotwork. i cant get good whips with the stealth so i had to get my black and grey shader and go over it to try and smooth it out. what stroke length would work best? and would that rotary the dude built work out for what im doing?