Would I be able to fit an inline 6 into this car?
not a huge one like a 4l from a Jeep, just a reasonable one like a 2.2l or something. If not, how about a v6?

 

sure you can ^_^
if you know how
but since your asking the question
im guessing not?

 

Well I was more asking what models of straight 6 I could put into it, cause I know some are tiny and some are huge.

I'd rather a straight 6 mainly because I've heard it's smoother and a little simpler than a v6.

And I asked because I wasn't sure if the engine bay in my car was big enough to fit it at all! But since I got you here, would the stock 5spd fit to the new engine? Would I need some kind of conversion kit between the two, or do I need a new transmission at that point.

 

a straight 6 is a rwd motor and thats long so noo
and v6 can fit but not a rwd one a fwd one yes but youll have to run a big hood scoop becuase there taller and stick out the hood

you didnt say what new engine you have?
but if its a stock civic one then yes of course a 5 speed trans will just bolt right up