Fixing the EM problems is going to be much easier than doing the conversion. No one is going to care about your converted EM, you'll never be able to sell it. Biggest probability is you ruin an EM, spend a lot of money, and never get the arduino working. EMs are basically indestructible.

It's a million times easier to fix the EM as is than to rip out a bunch of stuff, wire it all up new, and program an arduino to do a bunch of stuff the game is already fully capable of.

I don't care what you do. It's your game. But in terms of workload, that's a big conversion for a meh game.

Jwilson did a conversion of his EM machine to a re-themed machine. It was a lot of work and I would guess that his skills in tackling that task where challenged.

It is a big job that may overwhelm, leading to a machine that could be difficult to roll back to its former state.

Fixing a EM is also a bit of a challenge too.

Given the options fix EM machine or convert EM machine to home brew, my suggestion would be fix EM machine.

There is a whole journey of learning the art of repairing an EM. One that can be rewarding in understanding how EM work.
EM machine will likely live longer than their solid state counterparts... They were built like tanks.

If you do decide to go the home brew route, there are many build article on this web site. They may inspire your imagination for building ideas.

Good luck on what ever route you choose.

Fixing that EM would take less than an hour. That's the route I'd go. EM games will be running way longer than anything using chips or electronics.

If the game is continually resetting on player 2, I'd clean and adjust all the player 2 score reel 0-position switches.