Prelude engine swap

I was looking online at engine mounts and stuff and a lot of them were for like around $400, the engine isn't actually an h series engine at all, it's the F22, and yeah they said you needed mounts but new suspension? Why is that? Really I'm only looking to spend like $800 tops, so I might be just better going with getting the same engine, it's actually a B21 I have in there right now which is better than the B20, it's got a lot more torque but anyway I found a used one for $650. thanks for the help guys