1300 is great depending on you.
Looking at your standard ratings it's simple to conclude that you are phenomenal in 3 Check.
Improving 3 check rating in very short time is quite possible. A friend of mine who liked King Of the Hill only and didn't like 3check started playing it with me some, they weren't too great at it, but now I have a hard time beating them. It's amazing how fast you can improve.
After becoming awesome at 3 check, hopefully, you have the skill to transfer your easy improvement in 3 check to your standard play.
It's my opinion that playing 3 check is very good for beginners especially because it helps them pay closer attention because of the added stakes. And when that happens the player inevitably pays closer attention to the game, making improvement much easier.
If you are going to choose a variant in chess to play the most that will transfer its skill to standard, 3 check or 960 is the way to go.
I hope this helped!
My 3 check rating is about 1280, once I get to 1300 is that like a good rating?