So, I just bought a 543...

I am a firm believer in running what you have, rather than wait, or spend big money to try to get "right". I wouldnt bother to change e-streets for rpm, they are the same head. Either is "too small" for a 543. Will it keep it from running hard? Nope. Will it be better with tf 270s? Yep. Can you have fun with it for months if you run it with e streets while it waiting for 270s? You tell me.