Another backspacing question

[oldspowered67C10]

I know, I know, this topic has been beat to hell but I just want some quick opinions on the subject.

Im getting ready to order some wheels for my 67 SWB fleetside. I think its gonna be brushed boyds f-09s 19x8s and 20x10s and after searching all the threads and measuring things a million times I think I have my backspacing figured out but Id like to run it past you guys to see if you think Im right.

Heres my set-up. In the front I have a coil-over set-up with POL control arms and CPP modular spindles(the kind that retain the drum brake track width) w/ 13" rotors. There all mounted to the factory cross member and at ride height(cross member about 3" off the ground) I have very close to 0 camber. I plan on 245/40-19s for the front.

In the rear I have the factory 67 rear end converted to 5 lug w/ conversion axles and the CPP 12" disc brake kit( the one with the C5 style rotors and the Lincoln calipers)on air bags w/ relocated shocks. The frame is notched and at ride height the axle rides up in the notch around 1", I plan on 295/35-20s for tires in the rear.

The trucks frame is boxed and lightly triangulated but otherwise stock(no Z etc.) and is fairly low but not crazy low(doing kinda of a resto-mod meets pro-touring type thing) and my goals are to make it as low as is practical w/ as much lip on the rims as possible. Im thinking that for the front Id like 19x8 w/ 4.5"bs and for the rear a 20x10 w/ 5" bs. Ive trimmed the front inner fender wells and dont mind doing some trimming in the rear on the outboard side but dont want to widen the rear fender wells.

Do you guys think this will work? Thanks for any input and extra thanks for any pics w/ wheel/tire specs.