What size driver do I need to power 8 strips?

Assuming you are going to put them in parallel you would need something at 43.8V and 3.6A. 1866-2374-ND has a 38-46V Range at 3.6A.

Driving them like this however does come with its risks. Should you happen to have one of the LEDs fail you would be sending too much current to the remaining LEDs. This can cause failure of additional LEDs and lead to a chain effect.

Driving them in Series would be a preferred method. The issue here is trying to find a single driver that would be able to drive 350V at 450mA. While we do stock a number of units with a 450mA output I am not seeing one that would do all 8 units. You would likely need to look at 2 or more series circuits for your application.