Need help with wheel offset selection

[JWG]

I'm installing a CPP 4 wheel disk brake kit on my '65 stepside. Of course, now I need new wheels and am about to place an order, but concerned with which offset I need.

I'm going to run a 20" x 8.5" front wheel with an offset of .3"
(20 X8.5 5-127.00 7 DGMCML)

The rear wheel is a 20" x 9.5" with an offset of .6"
(20 X9.5 5-127.00 15 DGMCML)


Front tires will be 255/40R20
Rear tires will be 285/40R2

Do these offsets sound right?

Thanks for any help!