I really don't see the advantage of inserts on a model A engine. Babbit is VERY forgiving and adjustable for clearance, not so with insert bearings. Modern cars have used inserts for the past 60 years but they run full pressure oiling with seals that work and a full flow oil filter. When the thin layer of babbit wears off the inserts it will require a major rebuild and the crankshaft will have to be ground to an undersize, providing that there is enough meat left on the crankshaft.
I have run the original babbit bearings on my september 29 for the 53 years that I have owned it and I have run the hell out of it, especially when I was young. After all the shims were removed in the first overhaul in 71 , I've sanded the caps twice to take up clearance. Anybody that says that sanding the caps won't work is full of you know what!!!! I would think that most model A engines have had the caps filed or sanded, probably more than once over the past 80 years . The model A was made simple so that the common man could make most of his own repairs. I overhaul my own engines and my september 29 hasn't leaked a drop of oil out the rear main in the past seven years.I don't drive them every day as they are only fun cars but if they break , I can fix them myself.