I used Motor Meister's 914-6 conversion. IT WAS FREAKING COOL. I had them rebuild a 2.2 L inline 6 with 165 hp at the wheels. They were able to slap the engine in there inside a weekend, after I made an appointment. These people know their stuff and are able to make conversions between 2.0 L and above a 3.8 L with over 300 hp. I payed aobut 7k for my 2.2 and it's still going as far as I know (had to sell). Morot Meister's also will do further modifications in addition to the motor for little or no charge. I was able to get my chice of cams and a slew of other modofications for next to nothing. The problem for you: Morot Meister is in Downey, California. I'd say it's worth the trip, but that's up to you. I know I had a ton of fun going out to Laguna Seca two or three times a month with my friends to rape them on autocross and time trials.
Have a good one.