It would be a small nightmare finding all the original install sources for some of my applications, but maybe it would be worth it.
After doing the RAM and SSD, you could do an erase-install-import-from-clone using Setup Assistant (not Migration Assistant). This will put a fresh operating system on your SSD and preserve all your data, apps, settings, serial numbers etc.
If you are not satisfied with the result you can then do the completely fresh install where you reinstall everything from scratch.
You will have lost little by trying the import route first and will avoid the pain of the completely clean install if it works.
I have done a completely fresh install twice in 13 years of OSX on about seven different macs, but I have lost count of how many times I have done erase-install-import.
PS I also have a 2010 17inch MBP and there is plenty of life in it yet.