People seem to like that Lisle tool, I hated it and bought a Schley Products tool and these very important pliers to remove the old seal. I've posted about it. I've don't this twice now. You get better at it with practice. This should not be the first engine internal work you do. Seal everything so carefully. I like doing this without removing the heads, as most of us do. However, if you drop one of those keepers and it goes into your sump you would have wished you'd just pulled the heads. Account for every one of those. I turned the shop stereo off so I could hear if one launched. I only had one scare. One hit the ceiling and I heard it land someplace away from the engine, so all good. I'd also do a compression check just to make sure your engine is up to snuff B4 investing all this time. No sense spending all this time on an engine with some other problem. I went with OEM valve stem seals and aftermarket Melling (Chinese) lash adjusters. The factory lash adjusters were super expensive, like 6x the cost of the Melling. Mixed results with the Melling. One vehicle fine and one still ticks. Also replace the rear cam seals. Plenty of posts here about the timing belt.