I assume you just want the look of the wide rim on the outside? That's a LOT of money for a little appearance change. I get it, because I wanted to run 275 55 17 on the back of my 69 short step and bought a 72 wider axle housing to make that work (which saved me money in the end because I was converting to 5 lug so maybe no comparison).
I am not a fan of swapping car parts into the trucks (ie 4 3/4" bolt pattern wheels and brakes). Custom axles are about $300 a pair and the labor to narrow a housing anywhere from $150-$300 so that's an expense too.
But... why not just run a 5.5" back spacing wheel and call it good? Actually, you can probably run a 4.5" back space wheel and it will be fine since the 69 axle is narrower than the 70-72. Just add 5 lug conversion and drums. I'm assuming you are converting to 5 lug? The 4.5" bs and the narrow axle would be equivalent to 5 1/4" backspacing when comparing to my setup of 17x9 5" bs. wheels. I know the 5" bs wheel would work with the conversion setup and then you're done without spending an extra $1000. (spend where and when you have to...)
