abn2060

I have been a Toyota truck guy for 30 years but recently picked up a 99 Silverado 1500 as a work truck. I am an old school guy and want to run 16" x 8" or 16" x 10" rally wheels but I'm having a hard time finding rims that will work. From my research I found out that newer Silverado's are hub centric (78.1 mm) and have a slightly wider track as previous Chevy trucks. So I need to find wheels that have a 78.1 mm center bore but I need advice on whether I need 5" or 4" backspace? I've searched eBay, Summit Racing and Jegs but not having any luck so any help would be appreciated.

Thanks in advance.