I believe I will be buying a parts car from a salvage yard in Kansas. If so, I will be shipping this car to Michigan. In reviewing the inventory of this yard, I found the rear section of a 64-65 Chevelle frame listed on their site. This frame has surface rust but is solid with both rear frame rails and the cross member over the differential.
If I purchase this part and ship it to Michigan along with my parts car, I would need about $435 USD and it would be available 115 miles from Sarnia or Windsor for pick up.
If anyone has an interest, It would be available in March. Please send me a PM and I maybe able to send a picture.