I like to grab gears, but it is also nice to just relax while you drive your antique and enjoy the ride, instead of worrying about up/down shifting.
Well you need to ask yourself a few questions:
How often do you plan to drive your car? Daily or Weekend only?
What was your car originally and is it a rare version?
What parts do you have handy?
What is you daily driver like? Do you like it?