I would just replace the contactors, just match the HP on your DP motor.. A quick Ebay search: https://www.ebay.com/sch/i.html?_fro...actor&_sacat=0
As far as balance, look at the balance when the RCP is loaded, the unloaded balance looks close enough to start with. My home built 15HP RCP runs about 1 volt difference on the legs when loaded.