Very nice there, much better than mine as I do not have a drill press, just a shaky hand holding the drill.
Yes, front mounted motors work well. I have trialed different front motor mount placings on several of my previous builds with wipers and the big motors.
Here is what I did with a another build (what?!? Again?!?), which is my current sim.
As I have not tested motors at shoulder height connection I cannot advise if there is any motion difference or less power consumption. There are other wiper - shoulder builds here on the forum, so perhaps PM those builders directly for advice.
Short of strength of gearing in wipers, they should have sufficient power to give you some motion, although, I ran my wipers at 23 amps max current to give decent motion, and had to put fans on the motors to cool them. I didnt break a wiper, mind you, I kept extra fat drivers off it, like over 110kg.
Wiper motors are always a good cheap start and then if you like move on to different motors later.
Also, a suggestion, get your hands on some extension springs of different strengths. I found adding springs, and put them in different spots depending on balance, helped alleviate some balance problems and also not only reduced overall load on the motors , but with wipers being a bit tender, seemed to chopped the gearing out on constant direction change. So a spring helped create enough of a constant load on it to reduce this.
Hi-jack thread time
Although, as there are metal gears inside yours, you may be ok.