In JJK With Naruto Powers - Chapter 89: Mechamaru Vs Mahito

A skilled but unfortunate modern-day assassin was killed in a freak accident. However, he soon found himself summoned to another world by an evil wizard, who had him possess the body of a boy as an experiment. After successfully planning the evil wizard’s downfall, he used the wizard’s body as a springboard to gain influence and power in his new world.

A scientific genius named Thomas Harrier was transmigrated to an imperial prince body after a car accident that took his life. He found out that he is in a world similar to our own with a timeline akin to early twentieth century. The body that he is occupying was the imperial prince of a failing empire who suddenly rose to power after a successful assassination attempt of his father. Unaware that the attack is just the beginning of what is to come. He faces many challenges throughout. Will Thomas Harrier be able to live his second life in peace while running an empire and getting it back to its former glory? Or will he succumb into a conspiracy lurking within the country's borders?

Expect some:

Cold war era techs.

Super battleship with advanced electronics, propulsion, and fire control systems?
Helicopters?
Missiles?
Modern medicines and equipment?
AC-130?
A nuke?
Challenger or Abrams or Leopard?
F-4 Phantom or MIG-21?
Colored TV's.

Everything!!!

PS. Cover not mine, I just found it on google.

This year, Ji Jingqiu is 16 years old.To survive, he envisions the Fire House Buddha Prison, plants a bodhi treasure tree, and embarks on the path of martial arts.Many years later,A brilliant light arises, illuminating endless darkness.A towering ancient tree, with emerald green leaves and a canopy like a pavilion, rises with glass-like clarity into the sky, supporting a divine realm of pure land, spanning countless ages, illuminating the three realms and ten directions.On this day,All martial artists under heaven look up to it, like mayflies seeing the blue sky.......“Within there is a bodhi tree, which I planted when I set foot in martial arts, and now it has grown to provide a canopy.”“I see everything in the world, and nothing is like me.”“That year, I scoured history books, this history without era, I looked horizontally and vertically, and saw those characters – ‘The world’s storms come from us.’”...— Excerpt from the autobiography of Ji Jingqiu, the proud sun of the martial arts world of today.

After dying, Chen Heng finds that he has transmigrated to an alternate reality: everything is the same, except the world is now a Wuxia world heavily influenced by martial arts! Not only this, he discovers that he has a Fantasy Simulator, from which he obtains rewards that make him incredibly powerful in his new reality as well. Martial arts, immortal cultivation, and overpowered abilities–all of this begins from a single simulation!