David-
I tried dropping the prototype SimJet 700 (when I had it here after Superman) in my Hawk just for a lark and it almost completely consumed the entire engine bay!

Conclusion: Putting a SimJet 700/MW 44 in this Hawk would be like putting a SimJet 3000 into the FACET 1200 trainer- overkill is an understatement!
Based on the size and construction of this plane, I would say something the size of Ewald Schuster's "mini-me" would be more appropriate.
B1-
No retracts for me- I've built mine for cat launch/belly land as John intended. (Cat launches are a blast anyways...) I'll have a look at fitting the fan based on your measurements later, and see what I can do about pics tomorrow.