ReStack was made to normalize stack sizes among certain groups of items. For example assembling machine stacks to 50 while chemical plant only to 10. This can't be done with a multiplier.
Usually stack sizes need to be set once, so i see no point adding multipliers on top of numeric settings.
I've noted to add rails, combinators and wires for the next release.
Any way to make it so everything has higher stacks? There are things like chests; plastic bars, circuits, science packs, sulfur, batteries, uranium stuff, that I'd like to have a custom stack value, or is this too difficult and not worth it?
Just get something like BigBags if you want EVERYTHING to stack to high numbers. Pretty sure it 10 times everything by default, and has config options to increase that.