$15k is way too low just like it's way too low for an engine swap. In that, you can do it for $15k as your starting budget but you'll have to cheap out everywh

$15k is way too low just like it's way too low for an engine swap. In that, you can do it for $15k as your starting budget but you'll have to cheap out everywhere, get lucky many different ways, sell the things you swap out and still have it creep upwards. Likewise, unless you're starting with a junkyard motor $15k is probably not enough. A proper turnkey conversion for a V8 Miata for example ends up right around... $40k.