NL50 3bet BBvsSB spot

This hand is too weak to 3bet. Maybe against someone who opens 38% of hands, you could use something like a 10-13% 3bet range against him. K4o doesn't not fall into this category.

I might consider calling if...
He opens 3BB AND opens 40%+

Talking about the 3bet range, given that he folds 79% of the time, if he doesn't really adjust, we might want to ramp up our 3bet% to perhaps 15% even.

I think we can get away with a 2:1 bluff:value ratio or maybe use an even more bluff heavy range like 3:1 due to his really high fold to 3bet. So for value, I would use TT+/AQ+ (4.7%) and for the other 10.3%, I could use hands which are barely strong enough to call. I think given his 4BB open, a lot of hands I would typically call with should now be used to 3bet instead.

(K7s-K2s, Q7s-Q2s, J7s-J2s, T7s, 86s+, 75s+, 64s+, 54s, J9o, T9o, 98o)

If you keep pounding away at him I think he may try to adjust to some extent (but in a limited fashion) so I would still expect him to continue folding 65%-70% to your 3bets. So the 2:1 or 2.5:1 ratio seems good in the long run.

I really would just prefer to fold hands like Jxs and 3bet instead Kxo, I prefer to have a blocker than a somewhat more playable hand. Is that wrong?

It's not necessarely wrong, but it also depends on his tendencies. If he NEVER flats 3bets and only folds or 4bets, then obviously we want hands that decreases the combos of hands that are 4betting. If he however calls 3bets a lot, then we want hands that play well postflop in a 3bet pot.

ifs

No fun to 3b TT and get 4b by a dude that folds alot to 3b. What would be your plan against a 4b with TT in this spot Imfromsweden?

If I decided to 3bet TT I would not fold against a 4bet. Ship ship!

If he's so tight I don't feel good about shoving versus 4bet, then I would just in the first place.

ifs

What about the size? What I used was okay or would you made it different?

I personally make it 2.5X IP (and I believe many of the other hand judges do so as well). Here you are deep so making it slightly larger is fine.

It also depends on whether
1) your opponent folds or calls or 4bets a lot. If he calls a lot, then our range should be weighted towards value and we should make it larger
2) Our range composition. With a bluff heavy range I prefer to make it small and with a value heavy range i prefer to make it large.