[Nux]

So, I'm in Europe and prices may be different.

But over here, a complete MFI rebuild is 2K. Complete rebuild of 6 heads is another 2K (incl 12 new valves, CNC grinding seats, shims etc). Line bore (if needed), cylinder hone and crank polish is approx 1K (maybe 2). So max 6K in machine work.

Then add new hardware of your choice. I don't see how a DIY rebuild comes to 15K unless you buy new cylinders/pistons etc.