Since the cards are equilateral, you're going to have to add a new system of reading to the cards, as well as a new way of shuffling. E.g. aside from reversals, you may want to eplore developing meanings for 'ascending' and 'descending' cards - those thar end up pointing right or left. These could also add a new dimension to readings, like, what if a card points to the right, how is it in relation to the card it's pointing to?
It seems daunting but at the same time exciting. Good luck with your project!
PS You might want to look into having them printed in bigger dimensions - 3.5x3.5 sounda a bit small for tarotists. There are sites like makeplayingcards which do custom sizes for an additional fee so you might want to look into that too.