Matt how did you go with your gauges also do you know anyone with a 4.25 crank for my ritter fixed the problem using Felpro 1008 gasket no puffer 10,5 :1 so shouldn't be a problem goingng to do a 4.25 stroke 4.125 bore build
Gauges turned out fine, they did upgrade me to their revolution gauge for both and now its reading fine, just odd. I haven't heard of a by one with the 4.25 crank in a Ritter, would be fun though, as long as its the smaller Chevy ends should clear or need minor clearance unless you have the 340 smaller main size then it might clear no problem, 360 mains might be close or need clearancing, not really sure. I almost went with the 4.125 to match my same bore as you.