Lalo,
Thanks for the information, it helps. You mentioned the engines you have found come with cars attached. Thats good!! If you bought a "donor" car you would have the motor, transmission, the rear end, and possible power steering and power brakes. You could possibly use the radiator and endless nuts and bolts in your street rod. If the car has a tilt steering wheel you can also use it!! Try and find a Chevrolet car with the small block and automatic trans...even if the trans is a Powerglide. They are only a two speed, but they can be made very strong. You could pull all of the parts from the donor car and use most of them in your Model A. Don't get down if the car takes longer than you initially expect. When you get the car running and can drive it for the first time it will be all worth the wait.
The model As you have found would be a perfect beginning and make an excellent street rod. (Thats what I have)

Keep me posted,

Harris

PS> Those 35-48 sedans you mentioned are very polular in the states now. They call them "Fat Fendered Rods"