The problem isn't your wheels, its your tires that are in question. Which measure 12.5" on a 10 inch rim. Ready lift says a tire that 11.5" wide on a 9" wide rim (with their wheel spacer) clears.
I think your tires width and diameter will end up being larger then spec. Tire width shrinks a little bit going on a smaller rim, but.. all that extra width has to go somewhere so I would think diameter would increase? Really you need to put it on to find out, or find someone else who has tried this exact setup.
Most likely your stock wheels have offset around +18 - +24. It would help if you listed what wheel it is.
*edit*
Wow, they don't recommend you use 4hi. Did you see that?