Bolt Patterns and Backspacing

[David67]

Hey would anyone know the bolt pattern for a '78 blazer? I have the front clip that I'm puting in my '67 and I'm going to convert the rear 6-lug axles to 5-lug and want them to be the same. I'm looking at the Coys wheels and planning on running 18x8 in the front and 18x9.5 in the back. I have been looking and found that the pattern is 5x5 but want to confirm. Also, the backspacing options for the front wheels are 4" and 4.5" and the rear 5" and 5.5" and was wondering how to find out which ones I need.

Thanks in advance!