Hey guys just wondering if its worth putting a 3k bigport head on my 4k in my ke70? I have heard people say it gives it more power I also have a webber carbi mild cam and extractors?

Depending on the age and condition of the head it should be fine. Should check with an engine shop to make sure the valve guides are ok and it will handle unleaded fuel.

Yeah, if in decent nick it would be worth it. You'll get more compression at least. If you can find one of the larger manifolds that will help too, either a big port manifold, or the middle sized one. Should be able to get one of those from a KE55