Gauge question
 

Hey guys i had a quick question I'm almost done with my ls swap in my c10 my question is im using the 90 suburban gauge cluster with electronic speedo what im having trouble with is finding the proper fitting for temp gauge in the pass side head i know autometer has fitting 2277 that will screw into the head but the temp sender for the suburban is 3/8 and the fitting only excepts 1/8" npt