Unfortunately, no body offers a drop in hyd. roller setup unless you use a magnum block and oem lifters.
If your carefull with lobe selection, lift, and spring needs you can get a solid roller to go 20,000 miles before they need checking.
I can't tell you how many miles my lifters are good for, but I'd say in the 20,000 to 40,000 before checking/rebuilding.
Just depends on the spring pressures, abuse, and lobe profiles...
