Whats the point tho? adding it in as a random option seems rather pointless, you might as well say reroll this result. That aside one or the other (psy or mines) seems to be the options, unless you wanted to add a rule such as "A roll of 12 allows you to choose your desired refit, if this is your first randomly selected refit you may choose your desired refit and receive it at no additional cost."
I still think the Psychic scream would be better represented either in the hive ship rules (as they are for hives only) or as a "fleet commander" upgrade similar to the necron sepulchre. The mines however also feel better represented in the same manner, as an option any (non adult or adolescent) launch equiped ships may take.