Seriously man if you're pressed for cash you'll be able to endure them, but you'll be much more comfortable landing all around and taking off switch with the longer ski... I'm also six foot and I got 180's, I had 174's last year but I regretted not getting the extra length, it really helps in the long run.  I also find it's much better for actual skiing.  Anyway in my opinion you'll be better off with the extra lenght, twins started off beeing shorter when they came out, but generally their a bit longer now because the extra lenght really helps when landing a big air, or the extra tail in the back when you're taking off.
However if your just staring out, a smaller ski for this year maybe easier to learn the basics on and then you could switch to the longer ski next year, or when you're starting to trick on the big airs and getting good height out of the park and the extra lenght shouldn't really bother you and you'll benefit from them when landing guaranteed.
AXIS BOARD SHOP!
MONT ST-SAUVEUR SNOWPARK!