You shouldn't need that heavy of springs for Ti valves. I am not a big time engine builder but one of the guys I work with does tons of CR450F heads that have basically the same size valves in it as a Gen II and they run about 42 lb springs.
He says that the heavier spring is harder on the Ti valves when using the stock seats since the valve material is soft and it is overall harder on the valve train if you do not need them. Guessing that is why the big boys (Schnitz) that are running Ti valves are using bronze seats.
Also I race in a "production" class so I'm looking at every little bit of friction etc. that I can take out of my motor. I'm not going to say what I run but it is certainly less that 65 lbs.
Definitely high quality springs with bigger cams is a must but heavier is not always better.
This is probably going to raise a debate with parties on both sides weighing with their opinions but I have big cams and run to 11,500 to 12,000 consistently and have never had an issue.
You will have to do the research on your combination of parts, what your engine builder says, your goals and how deep your wallet is then decide.
