Quick Question - How to event on multiple clocks rising edges?

As there is a Fifo in play, the solution can be as simple as:

Use a DCFIFO of 24 bits wide and write the data into this fifo with the slow Clk1x.

Then at the read side use a clock of at least 3 times the frequency to read 24 bits out of the fifo and multiplex the 24 bits into packets of 8 bits.

Don't try to dodge clock domain crossing (as Tricky advises), it will come back and haunt you (no pun intended with the upcoming Halloween frenzy).