Attaching wood to block

I need to attach a 4ft length (actually several) of 2 x 6 PT lumber to a block retaining wall. These will act as the supports on one side, for some steps/platforms leading from my back yard to my alley trashcan access. I can't put posts due to the footer and drainage pipes in the area. I'll put posts on the other side of the steps to support that end. I'll be using 2x6 or
2x8 (approx 30" wide) for the actual platforms/steps themselves. It will just be me and bags of trash going down the steps, lets say 225-240# max.

Heres the question,

How should I attach the 2x6 to the block? I was planning on adhesive and Tapcons to hold the 2x6 to the block, then I remembered I have a Remington
powder actuated tool, and that might be easier/faster. Which would be better, and what adhesive would you recommend? I think I have Liquid Nail, PL and Sikkens(? Its over in the concrete area of the Box store) adhesives available to me in this area.

Thanks Guys

 

I would use lag bolts with expanding anchors, nails and glue don't cut it.

 

Thanks for the reply Frank.

Concerned about cracking the block tho. 1st 1/2 course is hollow, the rest is mortar filled.
Have a test in progress. Didn't crack a spare block with a green load and 3" nails. But nails didn't penetrate all the way. Going to try yellow loads and lightly shorter nails tomorrow.
No hurry here, plenty of time to experiment.