Since the hope is that Downs will fill the 2nd base position in the not to distant future, ala July of 2021, why not fill with Chavis, Chatham or Lin? I have yet to see any other, including Munoz as better option.
As far as outfield, it would be a reasonable approach to sign JBJ on a team friendly contract, but that is a iffy proposition. I by no means am convinced that Beni is our outfielder of the future so I would look to fill at least one outfield slot. If Jarren is ready then he would be a good fit. Either use him or lose him. I think the Sox have seen enough to do the former and in 2021.
My approach would preserve the majority of money for Pitching. At least one quality starter, a closer and several relievers.