if you use the conversion kit with the holddown and the dogbones,you will need a small base circle cam.
If you get the link bar type hyd. roller lifters you can use a regular hyd roller grind.

the lobe ramps are much more aggresive on the roller cams over the flat tappet camshafts Rick.

I have seen hyd roller cams used with solid roller lifters,I've never seen roller lifters used with flat tappet cams(or vise versa).

If he has the cash to buy the link bar lifters,I'd go roller if not then just order a flat tappet cam kit.
He will need different lenght pushrods for the roller setup