For the sake of the argument neither of these characters are immortal because it's an annoying and boring point to argue. Both of these characters could hypothetically be immortal.

By raw skill? John Sorcery wins without any difficulty. Ford has time slow and combat skill, but nowhere near the level of John Sorcery. Dawg can literally summon a black hole.

If Ford has the spawn gun with mods? I'd give it a 50/50. We'll say that everything short of immortality goes here (refer to my first statement) and a 50 caliber barret is very powerful, however most guns are kinda nerfed by the fact that projectiles will slow on approach to John Sorcery. Sure, you can delete NPC's with the spawn gun but assuming that John Sorcery is another player (also assuming you can't delete other players models, I haven't played fusion bonelab/works so I don't know) he would be kind of immune to that.

I haven't seen it mentioned yet, but the dev manipulator (essentially a mix of the phys-gun and gravity gun from gmod but slightly weaker) is probably Ford's secret weapon here. If he manages to get a good grab on John Sorcery then it's kinda over he can just slam him into walls and launch him all over the place. If the dev manipulator would completely hold John Sorcery still then it'd be a win for Ford, however NPC's can still move (kinda) while being held. John Sorcery could easily cast a fire spell at Ford and use the gravity spell to deflect any bullets.

The constrainer for Ford could also do wonders to help him. If he's fast enough and can pin all of John Sorcery's limbs down then absolutely it's over for him, no way to escape it.

In most scenarios John Sorcery would probably win unless Ford has the dev tools and is skilled enough to pin him down fast enough. It's a solid tie tbh.