Wouldn't help if the passages behind them are only 1/4 ".
You could possibly take it apart , re-do the innards and do a diaphragm kit while you are at it........but by now , a new pump would make more sense.
Personally , I think a mechanical is marginal for 600 h.p. unless you use a pusher too.
Might work , but I'd rather go with a nice electric.