Here's a sample of the result of low pass filtering THX 1138's chroma to 843.75KHz (that's 1.6875MHz together which is basically DV's 4:1:1).
This isn't what LD is capable of (>1.3MHz for I and Q), but it's double S-VHS and the rainbows disappear, so it's good enough for me!
http://screenshotcomparison.com/comparison/125913
Note: No 3D comb filter was used here. This is 100% spatial.