good way to think about it, specially for pretzels, thats exactly how i do them. just never thought of describing it that way.
anyhow, 270s really arnt that tough. sliding unnatty is SO easy. whats hard, is actually jumping and turning to land it. by spining on, it almost gets easier.
but yea, nice wide box, LOW. decent lip, you want some pop.
come in low, ready for the attack. at the lip, pop, bring your hips around. you should be able to look down/back and spot the rail. this helps you stay lined up. once you hit, your head should naturally just float around, and youll prolly 270 off. youll almost certainly slip out onto your hip, or spin off the box and fall. either way, expect to take a couple diggers before you clean them. they are super fun though. go for it!