Jason, -12 is quite larger than -10 in relation to fitting and line size. With what you are trying to do under the hood of your SHO, I would definitely use the -10.
I just snapped a pic of a -10 fitting ontop of my -12 fitting on my Cobra. Hopefully this helps...
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Sal Mennella
CSX 4241, KMP 357 - sold and missed, CSX 4819 - cancelled, FFR 5132 - sold
See my car at CSXinfo.net here >> CSX 4241