Rake is determined by the angle that the factory chose when they welded your steering head to your frame. This swap will only noticably effect your rake if the forks are radically longer, or shorter, thus drastically changing your front ride height. (Think Eazy Rider Chopper)
Have the seller measure from the center of the front axle to the top edge of the fork where it clamps into the upper tree. Take that same measurement on the forks you have now. (Remember that the forks have to be dangling free with no weight on them when you take this measurement. Better yet would be to remove one of the forks to measure it.) If the new forks are as long or longer, you'll be able to set them to the same ride height you have now, so rake will remain unaffected by this swap.
What you're worried about more than rake is trail. Trail creates the self-centering effect that your front tire needs to give you stability and confidence. Too little trail and your bike is a twitchy, tank slapping killer. Too much trail and the bike becomes very hard to steer away from a straight line. Actual trail is really difficult to measure, so instead you measure what causes the trail. Take the nut off your steering stem where it goes through the upper tree. set a straight edge across the leading edge of the fork tubes. Measure from the front edge of the steering stem to the straight edge. Use a set of vernier calipers for this, because it's critical. Check the other set of forks the same way. If you get the same measurement, you'll get the same trail. If you get a different measurement, I wouldn't suggest doing the swap. A set of adjustable triple clamps could make up the difference, but they would cost as much as you'll probably be saving by buying the Ohlins forks used. At that point you'd be better off just buying the correct year Ohlins forks you need.
Yeah, the part numbers are different from Ohlins. That makes sense, since one set of forks takes radial calipers and the other set doesn't. But like I told you in the PM, that doesn't mean the new forks won't work in your current triple clamps. Are both sets of forks the same diameter where they get clamped by the upper and lower trees? If so, then the new forks will fit your current triples, thus eliminating the trail problem if you set the new forks to the same ride height as the old forks. If the new forks fit your current triple trees, the only issue is how far apart the forks are from each other. This would have to be the same in order for the front wheel and rotors to line up properly.
Ya know.... If I was standing there with a vernier caliper, a tape measure, and both front ends, I could tell you if this would work in about 5 seconds.