Lovell.......bowling shirts, like most things people collect are valued along similar lines.
1. Rarity
2. Quality
3. History
Without laboring the point, most everything you need to assess fits into one of these three areas. So..and in reverse.
3. History - well of course we all know the great mans bowling history and status in the sport - and sadly combined with the fact he left us far to young - this box is well and truly ticked.
2. Quality - to be really worth something the item should be mint and [should circumstances allow] preferably in original packaging. In this case we can scratch the packing and for the sake of the discussion - despite the reality that for a short time the item was actually on YOUR person [depreciating the value alarmingly I would suggest] - let's assume it was in "good" condition
3. Rarity - hhmmm, well given the great man gave a shirt to YOU Lovell - this might suggest to a cynical observer that he owned hundreds of the darned things!!! However we won't belittle the gesture with negatives - we will assume there are perhaps a few dozen of these shirts available. Which if you do the math makes them relatively rare.
Thus - taking the above into account - very likely the item could fetch $300 - $500 - a lot depends on where you try to sell it of course. If it was mint - and even without packaging [and in this case if I did find an Earl Anthony shirt still in packaging I would critically question it's authenticity] - and did not have the burden of history of being worn at one time by someone else [aka Lovell] - then maybe as much as $1000.
Nice gift - cork head!
Jones