Generally flippers by most designers are 7" from shaft centre to shaft centre, but Trudeau likes to stretch that out to generally (I think) 7 1/8".
Also using thin wire guides allows for more room to add another inlane as well as modifying the outer guide from timber to steel which on many games they vary the lhs of the shooter lane but on this they also modified the lhs playfield support timber to a thin gauge steel divider to get some more room for that extra 4th lane.
I think the slings are a result of what room there is left - balls need to fit down the closest inlane, balls need to be directed from the upper playfield to the start and mid of the flipper and the height / or depth of the sling is decided on which lane the ball will bounce and drop down - difficulty thing. Also the outer drain lanes are quite open so a wild ball could still be drained fairly easily even though it has 4 inlanes.
sort of a wide body feel to a regular body width.
here is a mini screen shot, but if a moderator doesn't want a technical section shown, just let me know and I will remove.
Edit - my apologies on the mini screen shot