seeking advice re: new Parallel start switch and solenoid

My new-to-me 1987 twin engine mainship has a momentary SPDT parallel start swtch controlling an intermittant 750A cole-hersee solenoid to combine my start batteries (each engine has its own group 31 starting battery which also supplies 1/2 the house load). The parallel system is not currently working and I'm planning to replace the switch and solenoid. My question is regard to posts I've read regarding folks who use a continuous solenoid (or switch) to combine the batteries to more quickly recharge both using both alternators - especially since the battery providing power to the refrigerator dischages more quickly. In addition to a continuous solenoid/switch is there also a SPDT helm switch that flips either way (powered by either ignition) and stays deployed to keep the batteries combined? I guess there is probably a small current draw to keep the batteries combined and it is obviously important to turn the helm switch off when not intending to combine. Is that why most systems are momentary ?(as well as the relatively brief duration rating of most intermittant solenoids). Or are there other problems with running as I've described. Thanks for any input.