Maybe we're all asking the wrong questions/offering the wrong advice. How is it that you like to fly/fight? T'n'B, B'n'Z, Energy fight, furball, cherry pick, combination of all of these? The answer to this will guide your plane choice. Above all, be honest with yourself. Don't worry about labels or what's considered dweeby.
You also seem to have a preference for cannons (as do I) but don't discount the .50 cal U.S. planes. They are highly accurate and effective weapons. 4x.50 are about the same as 2x20mm Hispanos. Most U.S. planes carry 6x.50.
BTW, if you're comfortable in the La-7 why not try the La-5 or the Yak-9U? Neither of these is labeled a "dweeb ride" yet both are competant aircraft. Many swear by the Yak (one of my favorites) and I've got a squaddie who fly's the La-5 almost exclusively.
As to getting bounced in the 38, it simply sounds like you need to visit the TA and get with the trainers or a dedicated 38 stick to learn how to control a disadvantaged situation. Obviously, this isn't always possible as the best sticks aren't going to give away an advantage but it would help you with 80% of the arena.
As to the K4, again, a trip to the TA using the .target command might help out your gunnery.
Don't give up. It takes time (11+ years for me and I still make mistakes daily) and practice.