If the forks are stock, start with stiffer springs and Race Tech cartridge fork emulators. For trail use, this is the best thing you can do to the bike.
You'll probably get 70 - 85 miles on a tank under casual trail and road use. Babying it on the road you might get up to 100. In deep mud or on the throttle all the time (pushing HARD on the road) mayble only 50 - 55 miles on a tank. As with any pre-mixed 2 stroke, if you are on the road, be careful about engine braking from high speed (hot motor + no cooling fuel and lubricating oil = seizure).
Make sure the linkage bearings are lubed. On the old style linkage, the upper rocker arm pivot is known to go dry and can be very expensive to replace and repair.
The '86 - '88 are reliable and run fairly strong when in good shape. The big bore 240 kits add lots of low end, but will usually not rev out as well as a stocker unless you port the cylinder. The big bore will also suck down way more fuel.