In this paper:
https://www.sae.org/publications/tec.../2016-01-1613/
Evaluation of the Aerodynamics of Drag Reduction Technologies for Light-duty Vehicles: a Comprehensive Wind Tunnel Study 2016-01-1613
They tested a range of cars model year 2013-2015 and found a 2-3% reduction in drag by lowering the nose by 20mm and a 5-6% decrease with a 40mm front and rear drop.
Based on this I would say definitely test first. Sandbags or otherwise. If you ever load the car down the rear will sag and have a reverse rake if you level it out. If that is something you do often it would be something to consider as well.
Stock image of OP's car:
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1973 Fiat 124 Special
1975 Honda Civic CVCC 4spd
1981 Kawasaki KZ750E
1981 Kawasaki KZ650 CSR
1983 Kawasaki KZ1100-A3
1986 Nissan 300zx Turbo 5 spd
1995 Chevy Astro RWD (current project)
1995 Mercury Tracer
2017 Kawasaki VersysX 300
2022 Corolla Hatchback 6MT
https://www.youtube.com/channel/UC6s...LulDUQ8HMj5VKA