Jeep cold engine noise

Everything else is in working order. It has a lot of miles on it but it still runs surprisingly well. My next question is whether or not my father and I could do this ourselves. If it is in fact a tedious job, we could probably get his mechanic friend to help us out too. Also, am I assuming correctly that we should just replace all the lifters, that way we don’t have to worry about the problem coming up again down the road?

For reference, my father and I have removed an engine from my Nova before and he’s done some engine timing work (with help form his mechanic friend), so we are somewhat competent.