Nice looking job Old Coot, I raised the rudder height on my cat 1/4" to reduce rudder surface in the water. may not work for you but does help get the lower pivot block up out of the way of prop. Turn fins work well also but will slow you down a bit Maybe .5mph. I put 2 on a 46" hull and it turns L&R equally well
Do you have a square drive on the clutch? If so you definitely need washers between strut and dog, if its a collet leave 3/16" to 1/4" between washers and strut. Grease everything!! its easier to wipe off grease than replace parts
Don't know much about the superior engine, but for 118$ you cant beat it. Get a tuned pipe for it and do some mods on the cyl, it'll really be fun then!!!
Nitropower