IMO, you have to put at least some on the Bucos. If nothing else, to cover what you played on the parlay. I have run into several situations like this already this year (and hit some rather large plays) and I always cover them a little when all I need is just one game that has not gone off yet.
If it were me, I would play Pirates +1.5 for 250 (or whatever you would be happy winning...with this play, you could potentially win BOTH the parlay and the Pirates +1.5) and I would put some on the ML as well. You may even want to play around with the alternate run line Pirates -1.5...that has to pay good I would think. Its all up to you, but I would at least play the Pirates +1.5 for the mere fact you could win everything....and you can't lose any money at all!