Logistical Optimists Wondering If We're Crazy

Hello everyone! My husband and I are taking a trip to Ireland next month and have everything booked. However, I'm wondering if we're a little silly to think we can make the first transfers happen as smoothly as we need them to in order to get to our destination the first night.

Our flight is scheduled to land in Dublin at 1140, and we need to be in Galway by 1700 to catch the bus to the ferry to Inishmore. The train that leaves Dublin Heuston at 1330 would get us to Galway with a little time to spare before jumping on the bus. Is it crazy to think we can make it from the plane to the train station in 2 hours?

How long does it typically take to get through customs on a Wednesday morning?
How long is the cab ride from Dublin Airport to Heuston Station?
Do the trains still run as efficiently and on-time as they did when I was there 10+ years ago?

Since it's our 10th anniversary, I even looked at hiring a car to drive us across the country in style. I'm willing to spend that much to make sure we make it on time and safely, but my husband would rather save it for us to spend on Guinness and Bulmers. We're not opposed to renting a car and driving ourselves, but the price on that is still a little steep for just a 2-hour trip and he wouldn't really get to see the gorgeous countryside.

So what do you think? Are we nuts to try to make those connections?