Sounds like your on the right track yes your right Dave will no doubt have checked balance etc before drilling the mount holes,as regards the adjustment of the strut you need an opened up slot where it exits the transom that way when you loosen that bolt it will allow the strut to slide up and down if the hole is tight round the tube then it wont move
.To be able to angle your rudder you just need to loosen the bolt holding the blade?.By all means add tabs if you want im just saying you dont need them
,keep up the good work.
Mart