Do not hesitate on a jm era marlin. Awesome rifles. Hearing the good things about new production (Ruger) but you want to pass on the Remington era guns.
I’d also steer you to the longer barrel length too, unless you really want that carbine. I have a few different marlins and just think the short barreled variants feel a bit club-like. Personal preference.
Although I have 45/70 as well, I am deciding on committing to a long term relationship with my 450 marlins, but I reload and need to stock a lifetime of components to be safe. The 45/70 by comparison is easy to find ammo for but for “max” performance you will still want to reload. I just sold my 444 too cause its just not getting used. I also have 30/30s and a 35 rem. All marlins. Be careful… its a slippery slope with levers! LOL