A 16 ga Auto 5 was made with that serial number in 1929, but it was not a Sweet Sixteen. Sweets were not made until 1937. Does your gun have a letter above the serial number or preceding it? If not, does the gun say Seet Sixteen on the receiver and / or have a gold trigger? If not, then your gun is the standard weight gun made in 1929. Auto5man
.032 on an 89. You can verify at partsamerica.com and enter your vehicle.
I would go with the V6. I have a Skylark that I bought with the 3.1 when it had about 63,000 miles on it and I've found it to be very reliable. The only problem it has is with water getting into the front passenger section on the floorboard. I couldn't find a cure for it, so I'm in there changing towels every so often.