My busbars are good for 120 amp per pole. In my case I am using lithium ion batteries which has low output current compared to lead acid. On your breakers there would be an IC rating usually between 3 and 15kA. That is a limiting factor on the breakers when using batteries. Lead acid can exceed 1000Amps easily under short circuit conditions. Always make sure that your total CC currents of your batteries do no exceed the IC ratings of you breakers. The busbars you have should have a current rating stamped on it unless you made it yourself. There is is quite a lot of considerations to take into account like temperature, insulation, enclosure type etc. which influence the outcome. There are charts available to put you in the ball park.