65 chevelle wheels

[lt1chevelle]

Here's what a friend of mine is running on his 65 El Camino. The info came off the Wheel & Tire Database (page 3) on Team Chevelle.
Car: 1965 El Camino
Wheel Make: Fikse
Wheel Model: Profil 5S
Front Size: 17x8
Front Backspace: 4.75"
Rear Size: 17x9.5
Rear Backspace: 5.625"
Front Tire Size: P245/45ZR17 Nitto 555
Rear Tire Size: P285/40ZR17 Nitto 555
Suspension mods: GW Tubular upper and lower front control arms with QA1 12-way adjustable coil overs and OEM GM front sway bar. Edelbrock adjustable upper and Curytrac lower rear control arms with QA1 12-way adjustable shocks and OEM GM rear sway bar. Hydratech Hydroboost power brake unit with 1970 Corvette master cylinder. Wilwood 12.9" front rotors and 6-piston calipers, Wilwood 12.2" rear rotors and 4-piston calipers. Richmond 7021626JB 6-speed (0.81:1 OD ratio) with a 3.07 12-bolt posi rear and superior axles.

is his car stock hight? i was going to lower mine 2-3 do u think it will still work? or will i prolly need a smaller sidewall hight? also it will be a 17-8 not 9.5 and the rims have 4-1/2 back spacing