Here are some options.
3.9/5.2/5.9 ENGINE - Lifters - HiPoTek
Hughes probably just re-markets these at considerable markup, but here’s what Hughes says.
https://www.hughesengines.com/Index/products.php?browse=search&search=5006&partid=11034
But as far as how safe the stock replacement hydraulic rollers are with high pressure, you shouldn’t have any issues. But Im surprised you’re not having more noise than just on startup.