Mechanical to Hydraulic lifters

Yes, you can do it. There's only ONE lifter on the market that will allow you to do it. The Rhoads VMax.

http://www.summitracing.com/parts/rhl-1068xl/overview/make/dodge

While they are variable duration lifters, they are adjustable. That means you can run them without the variation and have no noise, I believe. Call Rhoads and see what they say. Their VMax flat tappet hydraulic lifters can be used with a solid cam, so I see no reason why the roller cannot.