The motor came in and it is smaller than I thought so I have tons of room to fit it under the hood. I am going to put it about where the picture shows. The Fuse block and MSD ignition will both have to be moved but that is a minor issue. It will be centered in there and not as close to the radiator but that is the only place it would sit with all the junk in there to get a picture. It gives a good idea of the size of the motor though.
The other issue is that the motor has a 4000 RPM limit from what I can find so that means I need a 3.9:1 ratio to give me a max speed of 70MPH. The biggest gear that will fit on the axle and clear everything is a 36 tooth. The smallest gear I can find for the motor is a 10 tooth. So that gives me a ratio of 3.6:1. Not that bad so I will probably try it out first this way and if the acceleration is weak I might try putting a mid shaft in to gear it down more. I would rather avoid that problem though since it would double the mess under the hood and I would have 2 chains and 4 sprockets to replace when they wear out.
I printed out a circle the same size as the 36 tooth sprocket and taped it to the axle to get an idea of the clearance available. It is a tight fit but it clears everything it looks like. I will order the 10 and 36 tooth sprockets this weekend so next weekend I should be able to fit them in place and see how they actually clear everything if they come in on time.