This is going to be interesting for sure and it should be a fuel miser. The horsepower you're dealing with is more than the 10hp Changzuki and a little less than the 17hp Centurion. The number of pistons you're dealing with falls between each of the above as well.
(The aero-challenged Changzuki returns about 115mpg @ 52mph (145@45mph), and Centurion tops that. Where will Tigon end up?)
Your T5 is a very good choice and the 3.27 is the limit on the spit rear gearing.
Very much looking forward to your body design and how that works into the overall curb weight / it all adds up pretty quick.
~CrazyJerry