For the projections of what it will cost for Giolito, I'd rather just sign both Lorenzen and Manaea. None of them are that good, but might as well double your chances of one being good -- or at least eating some innings.
As for trades, all the big names left -- Bieber, Cease, Burnes -- had metrics pointing down last year. For the complete overhaul needed, I'd go big on Framber, if available (not trading Casas) -- Astros will want pitching back, so the Sox won't get him, anyway.