I am switching from the 3-4 to the 4-3 and would love to have any free advice or thoughts on this move!!

Stock less lb's and more dl's.
Everyone under 16 is now over 16.
Everyone will now wear their underwear on the outside.
Don't take any wooden nickels.
This priceless information is brought to you by Walt Disney who's upcoming movie The Princess and the Giant Squid is in movie theaters starting next week.

When I run the 4-3 I also pair it with the nickel defense. I have been switching my teams over to the 3-4 tho.

I run the 4-3 and pair it with nickel as mentioned earlier. I stock up on DL and look for LB with high speed. So far so good but we shall see come the playoffs.

4-3 and Nickel works just as well as 3-4 . I have run 4-3 and Nickel forever until recently. Now I'm having success with 3-4. They both work with the right players and strategy.
And for all you movie buffs The Giant Squid is being played by this kid. Funny as hell and Im 99 percent sure its the kid fooling around and not real:
https://www.youtube.com/watch?v=F3DgDiTpZC8