Just got a marmot fusion 30 in long (for people up to 6'6"). I'm 6'5" and it has a lot of room. I can lie in it with the shoulder drawstring around my head. I would always go for a long version despite being able to "fit" in a standard length. You compress the foot of a normal length bag resulting in cold feet.
Rab do several models with similar temp ratings, but different internal volume. I looked at two different 3 seasons and one was too small the other was about right. They were both supposedly made for up to about 6'1"ish. I think one was the Q400. The smaller one was about 600g in weight and the bigger one was about 690g.
The following companies do longer versions: -
Marmot, Rab, ME, PHD, Alpkit, mountain hardwear (I think), macpac.
Although probably special orders. Go to Outdoor Warehouse website, might still have a few long marmot bags on sale. Give them a call.
I think there is a company in Grange, Cumbria that refurbs bags. If I remember rightly they can also modify own bags to your specifications such as lengthen, increase filling or replace with better down. I suggest as a last resort google for them. They specialise in mountaineering bags, high end.
