We still need to determine what type they are. Are they fantails? Orandas? Comets? Shubunkins? What? Please google images to get some examples. Are they long-bodied (like pond goldfish, comets, sarassas, shubunkins, etc.) or short-bodied ('fancy', fantail, telescope eye, ryukin, lionhead, ranchu, oranda, etc.)?
The care and possible tankmates is very different depending on what type of goldfish they are.
If the pond is large enough they don't need a tank for the winter, a floating de-icer is all that is needed for many ponds.
What you could keep with them varies according to type of goldfish and tank size. Are you asking if you kept them in the 55 what could go with them? If so, what type are they?
Do you have craigslist or an equivalent? That is a good way to get them a good home that you could 'interview' and know they will be well cared for and stay together.