Suggestion please for Rally tune on ST185

Hi guys,

Any tips to boost my Toyota Celica GT Four from 1982 (ST185) for racing on all terrain on 4WD?
(around 900points or above)

Looking forward for suggestions
if anyone is good - Gear rations and other setting suggestion would be nice too

Thanks for tips

ST185 needs stock transmission to be competitive for 900PI due to the capped top speed allowing more PI to be allocated to power/handling/whatever.