To answer your original question:
Pat touched on it when he advised using solid roller lifters. That's fine if you're a builder and have solid rollers laying around that you can use. For the home builder, that's not an option. What I and others have done in the past is to disassemble two lifters and remove the innards, replacing them with shims or spacers of the correct diameter and thickness to shim up the interior of the lifter body to the bottom of the pushrod cup with the snap ring installed. It's difficult to shim to the exact point where you can get the snap ring seated, but you can get close. After your PV checking, you can return the two lifters to their original use as a hydraulic and go ahead with the build. Optionally, if you have old hydraulic rollers to spare, is to disassemble and fill with shims or JB Weld, then replace the pushrod cup and snap ring. Using JB Weld, you can get it dead nuts. These will then become toolbox items to be used in subsequent builds. You could check with some of the local automotive machine shops. They may have a couple of hydraulic rollers they will give you or sell cheaply that you can modify. Make sure they are the same length from roller to pushrod cup as the lifters you will use so that effective pushrod length (lobe to rocker) will be the same as the length you will use in your build.