Alex,
aaaaak57 is right here. Sounds like you need to try a milled thumb. If you get the shape of the thumb right, you can have it "worked out on the sides" and not use excessive tape. I would caution, that using 4-8 pieces of tape at this time of year, with the weather cold/cooler is probably a good thing. When the weather warms up, much of that tape will come out.
Also, no, forward in and of itself will not lower your rev rate. Forward pitch in combination with too long a span, wrong shaped hole, not enough bevel, could lock you in the ball, and cause you to lose revs.
There are people on here who can point you to a good ball driller in your area.
--------------------
Mike Austin's Precision Pro Shop
Houston, TX
Drilling and Tech Advice BirdDogbowling.com
Driller to many "Stars" and Tony Melendez too!