Venus should not have any problem with side mounted engine.

If you don't mind a little work for side mounting, go for it. You may need to add a little weight to the left wing, but it depends on how the plane flies.

Some of Birdie (spelling?) kits mount the engines up right.
Any plane can have side or upright mounted engine although they are designed for inverted mounting for enclosed engine and look. Very slight or no difference in drag when the engine head sticks out of the fuse.