David, When I did the same job on my 75 25 Mk 1 many years ago, I simply unscrewed the gate valves from the through hulls and brought the valve with me to my marine retailer and matched the threads to reinstall the new valves.. Since most through hulls are bonded to the hull using some impenetrable goop like 3M 5200, you'll risk damaging the laminate if you try to muscle the through hull out of the hull and I had no issues unscrewing the gate valve out of the through hull threads. I was informed by folks much smarter than me, that gate valves can be very prone to failure and when they do fail, there's no means of shutting the flow of water through the valve. Rather than questioning, I took their advice and got all the gate valves out of the boat.
Chuck Gilchrest SV Half Magic 83 35 Landfall Padanaram, MA
_______________________________________________ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
