couldnt you mark the belt and pully so they end up in the same place after

if the head gaskets gone, which is very common on saxos and 106's you also will want to remove the rad and have it chemically flushed cos they fill with sludge

also use some flushing oil in the engine for a few miles after to remove the mayonnaise that gunks it up.

the head gasket job itself is fairly straighforward, and the parts are cheap.