Twistas, I did it two boats ago on a Seasport with Volvo I/O and Yamaha 9.9 High Thrust, fuel lines do not need to be hard for I/O, flexible is OK. Last valves I bought I got for about $20 from PA Marine Supply which is now out of business but I would check with SeaMar or any other reliable discount Marine store, West Marine, Boaters World and some of the other well known stores are a little too proud of their stuff for my pocket book, if you are on the OP check out Admiral Marine Supply in Port Townsend, they cost way less for exactly the same thing. In re-reading your post I see what you are talking about by hard plumbed, just put a nipple on then attach the flexable tubing. Email me if you want and I'll be glad to take a photo of the setup I have now and email it back to you.