Whats required to do this? Worth the effort? Anyone know the estimated HP gain?

You'd have to:
1. Check that either valve is interchangeable as per part number. Length has not changed.
2. Do the shim buckets have the same part number. Says the lobes are not smaller so who'd use a bigger bucket pushing more mass with a narrower nose?
3. Springs remain the same so what lift/ramp/hang time has changed that drastic but a few numbers.

Is it worth the tiny bump. Answer... Its for racing moves like these, that are fine little adders to increase hp by fractions. And then a fraction here, a fraction there and you may/may not gain HP.

And something like that would be, hogging out the port, then find out the factory knew when the Bernoulli slows down filling up the port and you lost that speed event.

So for racing yes, for street, no. It may show it on a dyno, but seat of the pants, it might be a slight linear change, sure, but I doubt getting a huge smile [is the expectation] after all is said and done.

Say 3 rides and you'll never feel the difference even if there was one. And say I've seat of the pants both cam sets by changing gens. The change was so slight. Same as changing the OEM tires with heavier rubber and that noticeable flick of the bike, and then gone in 2 to 3 days, as if nothing.

Just put the whole Gen2 engine in. That's my plan.

Hub is correct. I spoke to a dyno tuner in Houston and he said you might get 5-7 HP. Not worth the money for that small a gain.