Tiresize and backspace!

I have a Chevelle SS 65 witch you all now (Sorry about my spelling,i´am from sweden!) have limited rear wheelspace,
I want to use 16x8 steel wheels with 245/50x16"
I have tryed to mesure backspacing a few times but all i got was an splitting headache,so help wanted!

I know for sure you'll be able to get an 8 inch wheel in there. A 15x7 Monte Carlo rally rim (Corvette style) will fit in there. Those rims are about 3 and a half inches, in and out. If anything, you should check how much space you have between the fender lip and the face of the brake drum, since the 65's have a lower fender "skirt". What kind of steel wheels are you looking at? Will they be custom made, or did you already find a set? I think you would be fine with 3.5 inches out, and 4.5 inches in.

The one i want is American Racing AR-767 but i haven`t bout them yet,the thing is i already got the tires 245/50x16"
it´s 5" from the drum to the "skirt" so it could work with 4.5 backspace but it is very tight!
especially the lower suspension bolt.

i have a 72 lemans (pontiac A body like chevelle) and i have cragar rims with 245/60r15s on the back and they still fit very good