You can run a roller cams in flat tappet designed blocks. You either run a reduced base circle cam and stock style roller lifters(not recommended do to cam stability issues) or you can run a standard base circle cam with link bar lifters.
Correct, but either option is quite expensive especially the special lifters. I'm also not a fan because you severely limit yourself when it comes to cam specs and you're limited to those special small base cams whereas with either "normal" setup you can get whatever cam you choose. Also, ask Rick Anderson what he thinks about roller cams as far as how high RPM cam stability goes....he revs them to 8k and will sell you the parts to run yours that high if your bottom end and block can handle it, and you can do it on OEM Ford lifters.