Most services hover between 215 and 230 lbs. fully kitted out.
Some services are as low as 205, and I have also seen quite a few with no limits, although that seems to be changing.
For reference, here are a few services I know of, what their limits are, and what aircraft they fly (all weights are fully kitted):
*I will also add, I obviously don't work at all of these services, however this is what I know from either their website or having friends who personally work their. If anyone notices any mistakes with the limits or mt listing of the airframe, please chime in and correct me, I don't mean to offend.
ATCEMS STAR Flight, Austin, TX - 212 lbs. EC 145
Hermann LifeFlight, Houston, TX - 230 lbs. EC 145
PHI Air Medical, National - 215 lbs. EC 135 and Bell 407 (multiple airframes)
Air Evac, National - 220 lbs. Bell 206L (they may use other aircraft outside of Texas)
Native Air, Southwest US - 225 lbs. AS 350, Bell 206L
REACH, CA, TX, and OR - 205 lbs. EC 135
CareFlite, D/FW North Texas - No limit as far as I know, AW 109 and Bell 222
Children's Medical Center of Dalls - No limit, Sikorsky S76 B
Cook Children's Medical Center, Fort Worth, TX - No limit, EC 145
That's all I can think of right now. As far as your height is concerned, you will be cramped in almost every airframe, however the AS 330, Bell 206L, and EC 135 will be the most uncomfortable, in that order. The Bell 222, Bell 407, Bell 430, Bell 412, EC 145, and Sikorsky S76 will be the most comfortable, in that order.
This is all my personal opinion of course. I have seen some big boys and girls squeeze into a helicopter and it got off the ground safely. I have flown with some of these folks, and it really does lower the cool factor to land in a helicopter and jump out with your partner the Michelin Man.