I would not use a 17" rim. If a 16" rim won't clear, use the spacer. Better yet, if you purchase a set of rims from Wheelsmith, they will build them to your specifications. They will also tell you how to measure your wheel/hub /brake assembly to determine whether or not a modified offset is necessary.
The 15" rims on your truck now are not the correct diameter in the first place.
According to the FSM, the original tire size for your truck is
6.00-16-6 on all four wheels
or
6.00-16-6 front and 6.5-16-6 rear.
Unless you've installed power steering on your truck, wider treads make it more difficult to steer.
To get a stock look, "bias-ply" appearance with radial tires, I use these. You get excellent stability and performance without the ugly radial tire bulge. In case you're wondering, I do not sell Diamondback tires. I've been driving with them on my Cadillac for 7 years and they are the best tires I've ever had on the car since I've owned it (20 years) I use it as a daily driver and have put over 30,000 miles on these tires.
I am putting these (blackwalls) on my 1950 3100 6.00x16-6 with 16x6 smoothies from Wheelsmith.
https://dbtires.com/product/auburn-deluxe-radial-15-16-sizes/http://thewheelsmith.net/wheel-catalog/smoothie-wheels
