When I bought my Gretsch set in 1972, I was sure that the stock rail holder was in a stupid place, so at 15 I drilled holes and mounted it right on top.
Boy do I regret that, and I ended up putting it back where it originally was.
I'll bet that near 100% of the people who drilled holes in old drums to mount stuff later wished they hadn't... so I'd strongly advise NOT drilling anything.
There might even be a visit from the Gretsch Police with baseball bats if you do.
How about a rims mount on a double floor tom stand on the right side of the bass drum to hold the tom, and use the other side of the floor tom mount to put your ride cymbal on?
I don't like my ride cymbal way up for many reasons, and prefer it in the stock low bass drum position. I like using double floor toms and that's an option that retains the vintage look and sounds good too.
But... I will say "drill it and you'll regret it later", I'd put money on that.