The AP case is from a VW transporter. The dipstick will be in the wrong location for a 914, but that can be worked out.
You'll need to change the FI fuel pump to something appropriate for carbs.
To get more power out of it, well... it's a bus engine. Almost anything you do to it will get more power out of it... it's 7.3:1 compression, so a good set of pistons/cylinders can bump that up. A better cam will help it breathe. If you have kronor to throw at it, cylinder heads... either a lot of work on the ones you have, or a set from a 2.0 914 engine. Weber IDFs will breathe better than the Solexes.
Answers are slow this weekend because the Americans on the board are having a holiday