not sure how big of a camshaft you are going to run. I have been putting hydraulic rollers in most of my customers engines, just because of like you flat tappets going flat. I have been using Morel hydraulic lifters for a lot of them, and one of the things is that a lot of newer hydraulic lifters need thinner oil to work properly. The Morel's have an instruction sheet and it says to use oils of a certain centistoke rating, which works out to be 10W30 oil. They adjust better and lube better.