Purchased a 6040z Chinese CNC in 2016 to teach myself the ropes of baisc CNC craft. Two years later, I feel much more confident and skilled but the learning experience took its toll on Y stepper with the Z starting to follow. I could go with the same size but was wondering if I could stretch its legs a bit and go slightly more powerful steppers without having to perform significant upgrades to the controller.

Below are the specs for what I currently have and what I would like to replace. However, I'm still a newbie when talking parts so I would like some guidance. I am willing to gut the controller if needed but hoping to keep the repair costs down so I can continue to learn.

Current:
FRAME: 57BYGH76/4A1.8N.m (aka Nema23)
LENGTH: 76 mm
A/PHASE: 3A
TORQUE: 1.89N.m (270 oz-in)
LEADS: 4
.

Proposed:
FRAME: Nema23
Length: 115 mm
A/PHASE: 3A
TORQUE: 425 oz-in

I can provide other specs from the controller if required