[69heavychevy]

I had manual steering and brakes in my 69 and absolutely hated it! Not much steering effort is required when going 20+ mph, but try parking in a tight spot and your going to wish you had Popeye forearms.
Sealing up a leaky steering gear is fairly simple, there's a sticky in the FAQ's section.
Unless your going to be strictly hotrodding/track/strip, I'd recommend you keep the power steering.