Here is a nice way to find projectors which can hit a 123" diagonal from 17.5' throw distance...
With a price under $1,500 overall.
You can read reviews on different models, but none of them are going to deliver the quality which a dedicated home theater deserves. For that I would be looking for a JVC RS46 (X35) or at the Sony VPL-HW40ES models which are designed for a better theater space like you have.
You mentioned the screen is 17" from the ceiling, but can you move the projector mount up/down as necessary? If this wasn't a 'cheap' theater the first time around, then it likely has a Chief or Peerless mount in it, which means you can buy a 1.5" pipe of any length as necessary.
If you have any RBE issues, then the Panasonic AR100 or Epson 8345 are solid entry level models with a ton of lens shift, and solid image quality... no 3D if you wanted that.
The Viewsonic models are entry level as well, but may provide an adequate balance of decent image for a decent price.
As for why most projectors in this price range are designed for 'directly overhead' projection, the answer is simple: In a room 12' deep, you can't put a projector 17' away from a 120" screen. You only have 12' to work with! So, a model with shorter throw distance is far versatile. The reality is you could remount the projector at 12' from the screen (probably) if you wanted to, but if you room is only 18' deep, then you couldn't mount any projector 20' from your screen. As sales seem to have shown, the W1070 gets a lot of love for being able to shoot the size it does from the distance it can, which works for far more people than it doesn't work for.
Still, you do have options that work from where you want to use the projector from. Just be aware that throw distance isn't the only issue, you also need to consider lens offset. The Epson 8345 and Panasonic AR100 both have a ton of lens shift. No other projector from that list has that feature.
IMO, I wouldn't go cheap on this if I didn't absolutely have to. I would get a decent projector, or if I had a decent projector, I would get it repaired.
For what it's worth, lumen specs are one of the worst ways to measure any meaning of projection quality. Especially with the plethora of 2x color wheel DLP projectors that can't really muster more than 400 or so color lumens after calibration.