It's all dependent on how quickly your players can develop in the early game. A T1 Parish in my cube is usually up to around a 3/3 or 4/4 before it becomes a must answer on the other side and that's mostly due to the density of cheap humans that are available in W/B Aggro in my cube. Perished will probably be slower since cheap zombies aren't as plentiful, but it might end up being more explosive in the later parts of the game if you have cards that can produce multiple zombies ala tokens. Parish can slot into more decks in a typical cube due to how common human is as a type across W/R/G, but I'm not sure if that's as applicable in your environment.
How strong are these? Both fit well in my format, but I'm kind of worried they're going to be too aggressive.
They are both aggressive one drops with high ceilings and low floors; excellent when deployed early and can benefit from a curve out, kind of ass in the later game when you're topdecking a 1/1 that needs help to be a threat. I think they're worth the inclusion simply because they introduce a new dimension of sequencing to aggressive decks that usually just end up caring more about stats than individual cards. The way I see it, the litmus test for an aggressive 1 drop is whether it can deal 3-4 damage throughout a game. If I can get that damage output before the one drop bites the dust, then it's been successful.
With the potential vertical growth you get from deploying either on T1, I'd say that they're well worth trying out due to the unique angle they provide for aggressive decks.
