I have read about all about the valve spring problems on the HP 500's. I have a 1990 HP 465, shoould I have the same conserns. I am clueless, witch heads do I have? What are my potential problems? What machining can be done, and what should I expect? If I only do a valvejob what should I replace, and with what? I am not rich but would like to stay on the water...

The hp465 uses a flat tappet cam and the spring pressures are not as high as the hp500 with the roller cam. It won't be as much of an issue, but the cam is still pretty big for a flat tappet(.560/.578) I would think you should have the springs at least checked in the 200-300 hr range. It also depends a lot on how hard it has been run.