Great news on the boat. I'm 6'2" and I hear you. My wife is a foot shorter which works well for us fitting into the V berth. I have never been uncomfortable in the boat due to lack of standing head room... well maybe once. I suggest the following rule... the seacover hatch is either closed all the way or open all the way... never half way. Ouch!
Which gate valve is stuck open? If it is one of the cockpit drains, I wouldn't worry about it. Others should be fixed but if I were you, I would enjoy the rest of the season and deal with it at fall haulout. (gee... after that advice I hope the boat doesn't sink in the slip!!) Have a tapered plug nearby in case of disaster.
When I bought my boat, the galley drain valve was cracked and held together with duct tape.
Since I was trucking the boat to it's new home, I fixed that right away.
Keep the info flowing!