Usually it is the other way around, putting in a bigger radiator to replace the small one. I would not do it, an engine needs all th cooling it can get with today's engines running so lean and hot, cooling is not something you want to downsize.
Listen to tennisshoes and don't do it.
Bigger is better.
Looking for a Used Sierra 1500 in your area?
CarGurus has 10,629 nationwide Sierra 1500 listings starting at $1,775.
Search GMC Sierra 1500 Questions
GMC Sierra 1500 Experts
Related Models For Sale
Used Cars For Sale