Convert fully proofed dough into madre lievito/ stable starter?

How can I transform a gift of fully proofed, natural starter pizza dough into a stable starter, perhaps in madre lievito form?

I was very fortunate to receive 300 gms of unbaked, fully proofed, wonderful pizza dough made by a 5th generation Neapolitan pizzaiolo; the original culture is the one his family has kept going all these years.I have eaten his pizza and the crust is superb. The unbaked dough smells wonderful, fragrant, and complex without sourness.  The attraction is partly because my mother's family is from Napoli; partly because this specific taste brings memories; partly because I'm awed by the care that has gone into keeping this culture alive for over a century; and partly because my own household enjoys natural starters that aren't sour.  It's probable that this will be the only time I will have this chance. I don't even know what method of lievito naturale this baker uses, hydration level, etc. I'm unlikely to be baking more than once a week, and when things get even crazier than baseline, I sometimes don't bake for a month. If I baked every day, I'd probably just try using it for 20% of a new loaf or batch of pizza, hold some of that fully leavened dough back for the next day, etc.  I'm definitely not very knowledgeable about SD/natural leavening. I was finally able to create a stable SD from scratch, thanks to Debra Wink, but I haven't used it in quite a while. I have read that the sourness of the final product isn't directly related to the sourness of the starter, but I've seen contradictory advice about which factors affect this. These days, I mostly rely on incorporating piece of fully proofed dough kept from my last bake (pasta fermentata), plus using the same bucket to mix dough without washing, plus about 1/8 tsp of old ADY  (so old it may be a "placebo") for a 2100 gm batch, with a very long cold fermentation.  Any suggestions would be very, very gratefully appreciated-- including how to divide the 300 gms into different "experiments", on the assumption that this might take a few tries.Many thanks,Panettiera