HI
I have now remembered there was a post on this site in 2010 on a Sea Scout renovation. I suggest you look at http://http://mdlbt.com/3664 as this build blog will answer many of your questions
Cheers
Dave

HI Impartit
The Aerokits range were around in my youth and were very fine kits in their day and still rightly attract many to their clean lines and sailing qualities.

We now have much smaller and more efficient motors and batteries than were available when the kits were issued. IC engines were very popular and required good access to allow for starting. As a result the mounting was much higher than is required today and as a result the prop shaft angle was quite steep.

With a modern motor you can alter the shaft so that the angle is less severe and aligns with the motor on its mount inside the boat. The other consideration is the size of the prop as the shaft has to exit in a position that allows for clearance with the hull. You do need to fit a rudder so make sure you leave sufficient space behind the prop. You may need to angle the motor slightly and its position will need to be adjusted to suit the length of the prop shaft.

The motor mounting can be attached to the hull or a wooden plate in the hull. if space is tight and screws are too long you may have to glue the mount in place.

Once you have the prop shaft in place and the prop attached you can position the rudder vertically in line with the prop, there is usually a small 5-10 mm gap between the rudder and prop. Make sure you have room to attach an arm on the rudder shaft for the rudder servo.

A picture of the model would help if more specific advice is required.

Hope this helps
Cheers
Dave