You'll need to check the back of the 273 crank where the converter snout fits into. The very early 273's had a smaller register and the more common, newer converters won't fit.
But I agree with the above post. It's not cost-effective to weld up the journals or, I beleive someone makes spacers for it. The 360 cast crank is plenty strong for most applications and you'll have more cubic inches and torque.