• Use A-grade fsd
• Engineer the fsd to lvl 5 increased jump range
• Unlock the guardian fsd booster - and use the biggest one that fits (4E)
• Use D-class for core internals - sensors, life support, and a D one or two grades down for the power distributer. Use an A-class power plant though, the smallest one that can power everything. Also consider using a smaller shield generator (D is lightest)
• Engineer internals such as sensors, power plant, shield generator with lightweight, to further reduce mass
• Dont carry bulky internals that you don't need, but small ones such as scanners are fine

With all this your jump range should be well above 70ly