Another wheel size question

[1969CST10]

I know there's a lot of posts about people asking about wheel offsets and backspacing, but I just wanted to see if someone could double check my wheels and if they know if they're going to fit or not.

I've got a '69 C10 with the CST package. Just installed the complete RideTech suspension system and plan to have a ride height of about a 3-4" drop all the way around. Also put on a drum to disk conversion front and back. Looking at Eagle Alloys 064, 20X8.5 in the front, -1 offset and 4.7" backspace and 20X10 in the rear with -21 offset and 4.7" backspace.

Thanks for your help.