Rex - obviously an option tho gets me anxious soldering a brake cable. if a throttle cable breaks it can spoil your day, but if a brake cable breaks it can spoil your life. Ian if you do solder it, at least clean it very well, make a decent 'birds nest' and use a hard solder (silver solder).
for minor front brake cable length problems I've used additional cable tensioners and spacers to avoid soldering.
Wouldn’t hard solder result in an annealed cable? I use plain old (soft) plumbers solder and flux, and a gas torch, it would have to be pretty high wattage electric iron to do the job.
The secret to making a good brake cable is to use the proper materials and properly splay the ends of the wire into the recess provided in the fitting, or make a “birds nest” as mikeb said, also as mikeb said this is not a job to take on lightly, it would be best to have someone with experience show you how to do it first.
The spline the brake lever is fitted onto affects the length of inner “showing’ and is a reason cables often won’t fit without modification.
Another tip, use a dremel with cutting disc to cut inners and outers. It does a great job.