How do I make a block roller

known ways that work is to use a reduced base circle cam, stock 5.0 hyd roller lifters, and the webbing from the roller block.

Something I think will work but I havn't had the chance to test it yet, is use solid roller lifters and not hydraulic ones. The solid ones don't use oil to stay pumped up, so it's okay that they come out of the lifter bore a little, I think.
I'm going to give it a shot, if you care to try before I do, let me know how it goes.

Not all 351 roller blocks came with roller lifters. You really need to check the block date of manufacture. The solid lifters will work, but require many other things like springs, pushrods, etc, etc made for a solid cam

Pushrods will probably need to be different. Depends on if solid roller lifters are a different length than hydraulic flat lifters. The cam and springs can stay the same.