Me, I don't worry about finding a shop, I do the work myself. That way I know it's done right.
Finding neutral is mostly a clutch adjustment. Both the worm assembly and cable. Proper lube of both are essential. The kitchen foil funnel and oil method is best for the cable, using one of those adapters that clamp on the cable and use a spray lube are easy but not very good. I do use the adapter thing to clean the cable, hook up a spray can of carb cleaner to spray through the cable, shoot in some, let it set then spray more till what comes out the other end is clear. Then lube.
On the worm remove it from the cover, look to see the way the arm points before you take it apart and as you take it apart. This way you can get it back together right. Take out the adjuster screw also. Now clean all the old lube out. Inspect for cracks or other damage. If ok lube with most any grease, I use whatever is in the grease gun at the time. reassemble.
When you have the cable and worm well lubes reinstall on the bike. Adjust as your repair manual explains. The only changes I make to that procedure is at the point you back off the adjuster, I spin the adjuster screw in and out a few times to get a good feel for how much effect it takes to spin the screw. I then slowly turn the adjuster in till I just feel an increase in the effort to turn the screw.
This is the point you have removed all the slack between the worm and pressure plate. This is just a touch tight, you want a bit of slack here to help prevent slippage. The book says turn the adjuster screw back out 1/4 turn. I use a bit less. 1/6 of a turn. As you turn the screw let the lock nut turn with it. Watch the flats on the nut. Turn the screw back one flat of the nut. Now hold the screw while you snug down the lock nut.
Now on the cable. At the lever turn the adjuster out to get about 1/8 inch free play. I do this by holding the cable and gently pulling it away from the adjuster.
This way you can easily see the cable end move in the adjuster.
This does put the lever out so it's bit harder to reach but it opens the pressure plate as much as it can open. This relieves clutch drag as much as possible and eases finding neutral.
The well lubed parts make it easy to pull.
On the low revs. As mentioned your ignition can cause this. On a bike that uses the mechanical advancer, such as all the points bikes as well as some of the after market ignitions, the lube on the rod gets old and dry and prevents free movement of the rod inside the cam. This can prevent the timing from advancing as it should, this can prevent full revs. Easy fix is to remove the rod, Watch how the alignment marks line up, The disc has an arrow, the advancer a line, Everything must line up as it was. Clean off the rod and the inside of the cam. When apart you will see into the cam. It has two bushings in each end, one is smooth on the inside the other has grooves. Clean out the old crud in these grooves and refill with fresh grease. Don't try to fill the whole cam with grease, just the bushings at each end. The rod itself just a thin coat covering the rod is ok.
Also it could be a carb related issue, air leaks can lean out the mix and cause low revs. Poor carb adjustments can also.
On carb issues I recommend you read the carb guide,
www.amckayltd.com/carbguide.pdf
If you don't have a repair manual I recommend getting one. Free from biker.net, I have that download plus some others as well as the factory books from 70 to 82. I have both the Clymer and Hayne's books. I prefer the factory books but the Clymer and Hayne's books are ok. They both have some errors in translation. These errors are why it's good to have more than one reference.
Leo
