You have some good parts to work with, the 89a-10s will work pretty good, maybe try a y/s/y spring and 3.4/2.4 rivets, gearing will be good for 1/8th, 51/43 with a red secondary about 70-80, you can try and go lower once your close and see if the sled picks up, the looser the better usually on the tar, it all depends if you suck the belt or not on take off. I didnt ask how heavy of a rider on the sled.
This next part determines how hard your going to load or apply load to the engine and chassis as one, what I do is put the sled on a concrete floor and lay a shop light(the flur. ones are great) next to the track, now go on the opposite side of the sled and lay your cheek and face on the floor, if you can see light under the track your losing traction in those areas. To get the skid to sit flat I usually take all the spring pressure off the front shock, the front shock is just along for the ride on asphalt, and tighten up the limiter straps, the move to the rear shock loosen it up till about 3/4" of threads showing, FRA adjuster in the stiff spot, now on the transfer rods add shims to the BOTTOM of the rods, this will suck down the rear of the skid and allow it to sit flat. You will also need to adjust the front ski shock spring tensions to get it all perfect from front to back.
The one thing to keep an eye out for is to keep about 3/8"-7/16" inch clearance between the ground and the drivers bottom, this way you wont bend the driveshaft if you hit a bump, you want the skid STIFF!