7 1/4 to 8 1/4..... easy?

I swapped an A-body 8.25 for the 7.25" I had. I had to shorten the drive shaft about 1.5". The doner car is likely a 904 and your 727 is longer so you will likely need to shorten the drive shaft. Its pretty inexpensive cost me $75 to cut balance and install new u-joints at the local driveline shop.

If you can get the shock plates that is the best situation but you can easily elongate the holes in the 7.25" to accept the 3" u-bolts. Most likely you won't get all 4 u-bolts intact, new ones are about $5 each at the local NAPA.

The yoke on the 8.25 will be the same as the 7.25 so no need for a conversion joint.