Need some help picking tire sizes for a 4/6 drop

[Mattchu60]

I'm thinking about buying some wheels and tires for my build today for my 87' C10. Going with Torq Thrust II's. Pretty sure I am going to go with 20's (wanted 18's but tire sizes for that wheel are really limited). On the Front I was thinking either: 1) 245/45/20, or 2) 255/45/20s (20x8 wheel). The rears I want to use 295/40/20s (20x10 wheel).

I'm pretty certain the rears will work with no issues. After reading a lot here I am somewhat concerned about the fronts. I'd like to retain the stock inner fenders with my build and my concern is about rubbing issues.

Drop up front is a western chassis 2.5" drop spindle and one coil cut off the springs - would estimate this at about a 4.5" drop.

The 245/45/20 wheels spec out to around 28.7" tall
the 255/45/20 wheels are about 29.1" tall

I would much prefer to go with the 255/45/20 wheels up front, but again - not sure this will even work. The backspacing for the front wheels will be 4.50 in.

Any input is appreciated - the web is running some sales on tires today so was hoping to wrap this up. If anyone has a suggestion of a different front size please let me know.