While I would never reuse old flat-tappet lifters (I be hard pressed to even recommend flat tappets – but that’s another post), I have and would recommend reusing rollers – with the caveat that they are serviceable. Roller lifters don’t generate a wear pattern in the same manner as flat-tappet lifters. GM dealers routinely reused factory lifters on a brand-new cams. If you’re building an existing roller motor, there is no reason to buy new lifters unless you just want to spend the money.
The lifters that you have are a first tier component and with 5K miles should be like new. They have the link-bar to keep things in the proper perspective. Just make sure they go back in the same side they came from – you don’t want to reverse direction that they’ve been rolling.
Several years ago I helped a young man with a real budget rebuild on a 350 for his pickup. The block was already prepared for roller ('87 or '88?) but was still running a flat-tappet cam. We bought 16 lifters, spider, push rods and rocker arms, and all the factory components from a U-Pull-It for $35. Used a new generic RV-cam from Sealed Power ground for 1500-4000 RPM. Soaked the lifters in oil for a few days and everything worked perfect. Granted, this was a real basic upgrade over stock, but certainly worth considering.