Congratulations JimG,
I am a proponent of the rifled barrel, but if I remember right your shots were going to be in the under 50 yard range and a smooth bore will hold it's own at those ranges and out to about 75 yards. It is when you are wanting to shoot 100 - 150 yards is where the rifled bores really shine with the new high performance slugs. The old foster slugs have a limit, as long as you figure out where that is and keep your shots within it, you will be very happy. Some foster slugs will be better than others and it wont break the bank finding out which ones work best. Once you find a slug that works for you, get the LOT# off the box and go back and buy as many boxes of that same LOT# as you think you will need.
Just make sure you de-lead your barrel with a bronze/copper brush and a good lead removing solvent. Once you get the sights set, check them on a clean dry bore vs a leaded bore. With smooth bores, right before season I like to shoot 3 - 5 slugs through a clean bore to check for accuracy and foul the bore, if it is hitting good I leave the bore as is until after season, then clean. If you can get consistant accuracy on a clean DRY bore, all the better.