Re: Spacing the engine up.
Assuming this is an outboard, there are several options for offsets and risers. Your primary concern will be your transoms ability to handle the added leverage.
I've seen a case where this was done to make a 20" motor fit a 15" transom and it seemed to work fine.
A simple bracket can be made from 3"x3"x 3/16" aluminum angle. It would consist of 4 pieces cut to the lengths you deem appropriate. Two would be bolted to the transom and two would be bolted/clamped to the motor.
The motor is bolted to the bracket at the bottom with a cross member of 2x4 across the top for the motor clamps. The two brackets are then joined on each side with bolts. You can have a series of holes drilled on the sides so you can adjust the height.
Alternatively, you can just buy a Jack Plate for around $400.00.