Stronglight made some pretty cranksets over the years & I considered using a pair of mid 50's Model 49D's on a build with a TA adapter/spider but I used them on a Roadie instead.
I have several different pair & love them all so I wholeheartedly approve of your choice.
The French pedal threads can be drilled out & re-threaded with proper 9/16 pedal threads if you have some BMX pedals that you really really must have on the bike.
While I am a devotee of another brand, I have a bit of a soft spot for the Diamondback & am glad to see that you were able to complete your build.
Congratulations on a fine machine.