Greg,
That is awesome. It will do exactly what you think it will do. You will be able to bolt up most Muncie and saginaw transmissions to that plate. Muncies like the sm320, sm420, rockcrusher, etc. You would also be able to bolt up a T-5 with a little modification, but may be a little light behind a 292. Another great choice would be the GM version of the A833, but you would likely have to bore the bellhousing out to 5.125, or turn the bearing retainer down to 4.686 inches. I'm not sure of the welding thing either, but there are ways around that for mounting pedals.
John