How much space

[chainmaker]

I am building a tadpole and I am going to put a HT66 cc motor on it I will have begun building the frame before I get the motor. I will be mounting it on a "tail"(an extension of the frame) behind the seat. My seat back will be at 45 degrees, the question I have is I need a rough idea of how long of a "tail" to plan for between the seatback and rear tire for the motor and a jackshaft. What are the dimensions of the motor with exaust, and carb. I ordered the motormount from Manic Mechanic today and I am going to mount the flat bottom part to the "tail" I am using 1.5 x1.5 square tube so I think this will work out nice. I saw somplace a outline of a HT motor with a measurment across it, You were supposed to re-size it and print it out so that the written measurment was the actual measurment to see if would fit your application, does anyone know where I can find this again??Sorry about the longwindedness ...but this is driving me crazy. I am just looking for a ballpark number.
Thanks for the Help
Chainmaker