I got 1 foot long of 1 1/8 inch" or maybe it was 1 1/4" diameter 6061 aluminum round stock from Grainger. My company has an account there (they don't sell to the general public) and there is a Grainger around the corner so I don't have to pay shipping. Otherwise I would have gone the
McMaster Carr route I also got the drill and tap from them to cut the 10mm threads. Amazon.com is another good place to find oddball stuff. I plan to experiment using a coupling nut to extend the mounting studs and try different lengths of pipe as a spacer to see what height I like. Then I'll cut the aluminum to that length drill, tap, polish it up nice and shiny, and bolt it up and enjoy.
As for engine work, if you're having someone do it for you, probably not worth the money. I would guess $500-$1000 depending on what you're having done. If you're doing it yourself, still probably not worth the money unless you just like to wrench on engines. To my knowledge they don't make any rebuild kits. You just have to buy the parts you need and then do it. I don't know why you would want to rebuild the engine unless you're looking for more power. Keep the valves adjusted and these engines are fairly bullet proof. Aside from valve adjustments I probably wont touch the internals of my engine until I hit 100K miles. If for some reason you need your engine rebuilt it's probably cheaper and easier to just buy a low mileage used engine and swap engines.
Caveat: All the numbers I'm going to spout here are from memory and may not be accurate. If you're making any purchase decisions on these numbers, do some searching to verify what I say is correct. If anyone sees something wrong feel free to chime in and correct me. Also the statements below apply to the EN500C The EN500A had more parts in common with the Ninja.
99.9% of everything between the Ninja and Vulcan engines are interchangeable. I say 99.9 because I'm sure there's something somewhere that probably doesnt fit and there are cosmetic differences. Currently my '94 Vulcan has a Ninja valve cover and water pump cover. The Vulcan 500 engine is about 40hp @ just under 8K RPM. The Ninja 500 is just under 60hp @ 9.5K RPM There are only three differences in the engines that yield these different outputs. First the ninja pistons are 10.8 compression ratio where the Vulcan's are 10.2. Second, the cams are different. Third, the ignition timing/rev limit are different. I know the "ignitor" modules are different, I'm not sure if the pickups on the flywheel are different but I imagine it's likely they are. I can say with certainty that the pistons, cams, and flywheels are 100% mechanically interchangeable. I never tried the ignitors so I don't know if they are plug'n'play swappable. Only reason i can think of why they wouldn't be is if their connectors are wired differently. Ok so I lied there is a 4th difference. The carbs are 34mm on the Ninja and 32mm on the Vulcan LTD.
At first glance the 50% hp boost with the ninja seems huge! Keep in mind that the Vulcan engine is tuned for more low end grunt (torque) at the expense of high RPM horse power where the ninja is tuned for maximum high RPM horse power which sacrifices low end torque. Neither is necessarily better than the other it's more personal preference of what you want out of the engine.
If you're contemplating an engine swap (Ninja-Vulcan), I can think of 3 areas that would be of concern:
1: Left side engine (stator) cover would have to be swapped from a Vulcan (I'm assuming the bolt holes line up, from picts it looks like it would simply be a bolt on, but I'm not sure) as the shift lever mounts thru this cover. Either that or you'd have to rig up something else to mount your shift lever to.
2: The output shafts are slightly different. I don't think this presents a problem but, you may have to use some custom spacers to get the sprockets to line up.
3: Ignition module (ignitor) compatibility with the ninja flywheel. Here you might need to swap the ninja flywheel with your Vulcan engine. I'm not sure if the wiring connections are the same, you'd have to study some wiring diagrams, but you could probably keep the Ninja flywheel and use the Ninja ignitor to get the ignition timing that is better tuned to go with the ninja cams and higher rev limit .