99 Chevy Intro wheels on a 70!!!!!

[bigcat842]

I've been searching thru the site and I just want verify that I can fit these wheels on a 70 with all drums if I add spacers(front and rear) or if I bore out the center of the wheel to fit the larger hubs. I am planning converting to 6 lug disk up front but not for a while but in the future it would be best not to bore out right!!! Would like some feedback asap please. These are the wheels!! Not sure the exact model but looks like the Intro Pentia 6 (20x8.5).