We'll, here's opening up a can of worms.
You will get a much better connection when the correct size lugs are crimped onto the battery cable using a good quality crimping tool.
Most people don't know how to solder correctly or have the correct equipment to do so. There is a little bit more to it then just heating up the lug with a blow torch and pouring the solder in.
As for crimping and soldering, yes it is a bit of an overkill, if the crimping is done correctly. If doing this I would recommend only allowing the solder to flow from the end of the lug/terminal to the end of the crimp. Don't allow the solder to flow past the crimp and down the cable.
My advice when planning something like this for your vehicle (if you are going to use B&S cable) is to work out the length of cable you require then drop into your local auto electrician and ask them to fit the lugs/terminals to the cable for you.
The above is based on the work practices I was taught and life experiences, my post is aimed at people who are not sure about the best way to approach this type of job.
I really don't want to get into a debate about soldering and crimping.
If you are happy soldering and have done so for years with no problems, then keep doing it.
After all, as long as the circuit works and you keep the smoke on the inside, then all's good.