Apply soldering past to the area you will be soldered. You can even put some on every end of the 63 pipes before you assemble them to the manifold pipes.
Soldering is a precision and a patience thing. take your time. It took me about 1 and a half hour, and I'm not a pro. (I'm an electronic automation eng.)
At each apposite end, solder some 1 1/4" fittings to enable you to screw an adapter in order to convert from 1/14 to 3/4" flexible pipe
the other ends will have a welded cap.
Notice that water must come in on one side of the first manifold, and come out on the other side of the second manifold. This will ensure that water will travel the complete distance. (like in commercial heat exchanger)