Easily would be on of the top matches in the exams , now i see this fight startin like this , neji takes his jyuken pose an activates his byakugan nd notices the sand carried in the gourd , gaara bein the impatient fellow he was would remark " Come on!"
Neji not takin the bait like rock lee would reply by sending two kunai flyin towards gaara's eye which subsequently gets stoped by the sand defense , neji then says "Sand! thats an unusual jutsu" while he notices the chakra flowin through the sand.
He then advances at garra while the latter sends sand waves which gets easily evaded due to neji's genius cqc prowes and speed , neji would then launch at gaara who would no doubt be in a confident poster with arms folded , fully confident in his ultimate defense.
Neji then closes the distance , covers his palm with jyuken chakra then attempts to hell stab gaara's face but before he could sand rushes to gaara and meets the attack before it could connect , only the attack pierces the sand much to gaara's shock who then activates his sand armor before the attack lands.
Gaara is then struck in the brain by jyuken , gaara achin in pain says "how did you!?" While neji replies with "things made of chakra or uses chakra as a component will be destroyed by simply puttin chakra into it , ur sand is useless before my gentle fist " before gaara passes out nd begins to awaken shukaku.
The match would end shortly after due to the jonin gettin involved.
Based on the way gaara fought lee in the chunin exams and iformation about gaara's gourd sand mechanics and neji's fightin style an jyuken mechanics it leads me to believe that this would play out with neji winnin low/mid diff im the chunin exam prelims , the fight could be very different in the finals with gaara preparing himself for the fight tho we still could not count neji out due to him also havin prep.