belt drives GT vs HTD

Okay,
I need some input from someone who has done this or knows more than
I do [doesn't take much]
I am building a point to point machine, was going for rack and
pinion drive one side . Decided that this application would be a good
candidate for timing belt on both sides of X.
Here's the skinny
Total Gantry weight 175#, riding on bearings with .006 COe
acceleration [desired] to max speed of 1000 ipm,?"sec/sec
I am planning 1" 3/8 pitch GT "captured"or belt held each end.
1" pitch dia. 2100ozin stepper turning that connects to both sides of
X. shaft dia is 1/2 in.
There is no cutting/sideload on Z as it is only for drilling thru
holes in wood.
Chart I have says a 1" GT belt is good for 184lbs. working force.
Any one see a problem with this? Have I overlooked or under
calculated anywhere?

thanks
CB