I was going to punt on this, instead here are my thoughts on all of it.

You have a lot of issues going on here which don't work well together.

1. You have specific requirements for throw distance and image size.

2. The throw distance and image size aren't shown as being possible with the projector you have listed, so something's going on.
See: http://www.projectorcentral.com/InFocus-Work_Big_IN26-projection-calculator-pro.htm
At a 120" diagonal, the IN26 must be between 15'10" and 17'5" from the screen. If you have it at 30', then you are severely hampering your currently installed projector.

3. There is a tremendous difference between ambient light business projection, and home theater use. Conference rooms look for about a 12:1 contrast ratio, which is only achievable with about 80 to 100 advertised lumen per square foot of screen space. Theater use looks for about 18 real lumen per square foot. That's a significant difference, and the design of the projectors is incredibly different to achieve those two goals. The compromise should be on the 'theater' side IMO if this has typical use for business, then theater night takes a back seat. It will still work, and look decent, but that's about all that should be expected, and calibrated settings can address that.

4. Measure about 5 more times, let us know if 'weird' lenses are in use with the InFocus, and make sure the image diagonal is correct. It certainly is NOT just a IN26 with a 120" screen from 30' lens to screen.

5. The use of a 4:3 screen is about half a decade out of date. I would not recommend repurchasing antiquated technology if you can avoid it.

6. The budget is very entry level. The cheapest projectors are under $500, but a nice bright projector which is reliable, and has a long warranty, and is more honest about lumen ratings, is typically several thousand dollars. You will take a hit on every aspect with the budget.

7. The number of projectors which can hit a 120" diagonal, 4:3 screen, from 30' lens to screen, for under $1,500 is listed as one. But, I am 100% sure that this is an incorrect price.
http://www.projectorcentral.com/projectors.cfm?g=1&hide=0&st=1&mfg=&p=150&p=1500&w=&r=&br=&ll=<g=&t=&db=&dt=&c=&ar=&dvi=&wr=&pjl=&pjw=&pjh=&td=30&i=d&is=120&sort=pop&sz=15

That projector costs well over $1500.

8. Ignoring the throw distance, and just looking for any projector which is 4:3 aspect ratio (bad) and can really light up a 120" screen...
http://www.projectorcentral.com/projectors.cfm?g=1&hide=0&st=1&mfg=&p=150&p=1500&w=&r=&br=4500&br=7000&ll=<g=&t=&db=&dt=&c=&ar=4%3A3&dvi=13&wr=&pjl=&pjw=&pjh=&td=&i=d&is=&sort=brt&sz=15

I've pushed the budget up to $1,500 as there is only ONE projector under $1,000 which is actually solidly bright.

I would recommend the Panasonic:
http://www.projectorcentral.com/Panasonic-PT-VX500U.htm
...and I would recommend you get it as close to the screen as allowable.

The Sony would probably have been on my list, but it is a 16:10 projector, which makes it very ineffective on his 4:3 screen. To fill the screen, you end up projecting off the edges, which loses a ton of brightness from the Sony.

http://www.projectorcentral.com/Sony-VPL-EW276.htm

This falls back to my recommendation for a new screen in the space, and perhaps a budget that is based upon the desired results, instead of a random number based on what someone sees at the local Office Depot.