Wheel Fitment

[panzonymariposa]

I picked up a set of used 20's off craigslist a few months back (wasn't ready to install them but just got excited to see some 5x5's on there) Anyways found out they were off a grand cherokee. I know now that the centerbore for the Cherokee is 71.5 and too small mount, but I cant seem to find what the exact centerbore is for my 79 C10. Is the difference minor enough that I can just get away with using a grinder to get them to fit or are these rims now destined to go on my gf's jeep? Thanks for any assistance