Plate and bolts. Get your gaskets locally.
The mystery coolant loss... yeah, familiar with that. I think it is one of the freeze plugs in the back of the motor. (cleverly concealed by the trans....) I have the same problem, but, not quite to as great of an extent. Freeze plugs in these motors are steel from the factory. They weren't real strategically placed, and get crap trapped against them, and they rust out, and start leaking. Generally only under pressure. Took quite a while before a couple of them started leaking enough I could actually FIND the leak.... Bypass hose from water pump to intake manifold is also famous for leaking..... coolant pools on top of the timing cover, so, you can't see it.... and it really doesn't drip that much. Such fun.
What kind of budget do you have for this particular project?