>>3087875Assuming everything even works as intended, you'd still be mistaken to think that medium format is just about the lenses.
In fact, MF glass is often more limited in capabilities than FF, and is one of the factors you have to work around when using such a system, but the results can be better when you do.
Even if you manage to adapt an awesome 645 lens to your a6000, you'll still be lacking the huge resolution and dynamic range capabilities of those cameras, putting it all to waste.
You really may as well just get a well-optimized lens within your own system or at most limit yourself to a FF/crop converter and spend the rest of your budget on a really nice FF lens that you can use normally should you ever wean yourself off that Sony shit.