There is no real reason for anything other than the OEM stuff, good quality of course, such as GM put on to begin with. Your money will be better spent on taking the radiator out, having it professionally cleaned inside and out, new hoses and belts, and a good fan clutch. Bringing the cooling system back to original condition is better than band aids to a system which needs basic service. (assuming it may need basic service).
My opinion, of course. (ex Argosy 28' MH, ex AS 310 MH, ex GMC MH)