People have been swapping V8s in Corollas since forever, it'll be just fine. Not to mention it only has about 400hp, or about the same as a well sorted SR20 or 3SGTE swap.
I've seen that black car in person. It's absolutely perfect. The car was built in the 90s way before Miatas were considered cool. Those fenders are massive, certainly one of my inspirations building my Miata. Here's a more recent picture.
I love those rear lights. One thing I like a bout MX5s, is that they can quickly go from a hairdressers car, to badass weapon, as proven above and below.
I love these.
