you would probably see more of a return if you spent that money having nearly every part of the engine ceramic coated. This is a fools errand. The VE pump is beautifully simple and capable of a lot, just look at what guys like Giles do with it. If you want a CDI swap the whole thing in, I'd subscribe to that thread. Why wouldn't you start this project with a direct injection engine if efficiency and the elimination of fuel pulse is what you are interested in. At least those are set up with sensors to run ECU's, I just don't think any of us understand why you want to do this. In any design project I think it is best to start with the problem you want to address and then determine the best (cheapest, easiest, most reliable) means to achieve that goal. You have put the cart before the horse. You have started with common-rail injection and are trying to come up with a reason as to why you should use it. Start with fuel efficiency, or reliability, or torque, and then research that. It is an old VW there will be plenty of time for thinking outside the box and rigging up junkyard solutions. I know we seem like naysayers here, but you asked if it can be done and the answer is a resounding not worth it, sorry if that is not what you wanted to hear.