Going back to the strike plate issue: This works for a lot of people and for some people the foam method works best. All I'm saying is this, move the strike plate back now that you have your playfield torn apart. If it works (most likely) then great. Is it doesn't, then you can simply add the foam and problem solved.
If your playfield wasn't torn apart already, I would recommend doing the foam method first because it could save you a lot of work and time and you avoid doing all the work by simply adding foam and lowering the saucer hole.
The foam method saves you a lot of work and time and its worth a try. But since you have your playfield torn apart, just move the plate back now since you already did all the hard work. If it doesn't work for you (most likely will) then you can add the foam and lower the saucer hole as a last resort. Good luck