The best setup for autocross on very small tracks

[Fii]

I have a '86 Levin Coupe with broken blue top engine in it (not sure what the problem is yet, but it most likely needs a full rebuild). I would like to build an autocross project car using my AE86 as a base for it. Most of the tracks here in Latvia are very small ones, so most of the time the second gear is used, the third gear is only used in a long straight once a lap. The car will NOT be used as a daily driver, however I should be able to drive it on street if I wanted to.

What would be the best setup for the racing described above?

Chasis
Currently the plan is to take everything apart, reweld the seams and get rid of the rust. Then paint it. Some weight reduction will be done by not putting the rear seats and the trim in the back of the car back in. Also some sport seats will be fitted in the front.

Suspension
I am planning to use the Paradise Racing coilover kit with Tokico blue shocks and Prothane bushing kit.
What spring rates should I choose?
Will I benefit from adjustable links or camber kit?

Engine
I feel that the engine for my target is not the most important factor. But everything else aside I think that low to mid rev torque is the thing that matters. What are the options to maximize the torque? I would like to keep the car NA, so no turbo or supercharging.
I see the following options:
1) Simply rebuild the blue-top
2) Get 7A-FE block and build a 7A-GE out of it (how much torque diference can I expect?)
3) Do the Black-top swap (mostly due to the ITB throttle response and VVT torque curve)

Any comments or suggestions?