oh, what a shame.

I think, porting the head is the most efficient thing to increase power, in relation to the costs, too.
Additional, you can replace your stock camshaft with a mild "hot" camshaft with an adjustable cam sprocket.
Megacycles and Webcam offers a lot of different shaped camshafts for stock cylinders and big bored one,
from the broad power range to top end. I will take a mild, broad power range (street) camshaft for big bore usage.
That's my way to go. The only reason is why i want to use a big bore kit is, that i have to hone my cylinders
and I have to replace my pistons and rings, too (+0.25 ??, don't know, don't like to measure or test compression),
so it's easier for me to rebuild the engine with complete new 836cc stuff.
(I own a second cylinder, so i could go back to the original size, if i would like).
Next and more expensive way would be to use Dyna ignitions/coils and bigger carbs.
But carbs,...not for me, I want to conserve the original look of the K1.
...you own an awesome nice 2 in 1 tank,....gives the bike a really nice and long stream line shape.
nippon