“A fool-proof method for sculpting an elephant: first, get a huge block of marble; then you chip away everything that doesn’t look like an elephant.” – Author Unknown

Ok, so maybe it didn’t take that much fitting, but it was a bit involved.
The slide release cleared the grips afterall. In my quick fit, I confused the lever’s failure to move downward with it’s being forced as far down as it would go. There is a tab that needed clearance from the back of the slide. In fact, this tab is what holds the slide release in when the slide is anywhere but at the magic take down notch.

The thumb safety took a little more work, though mostly because I wanted to sneak up on the proper relief and not risk over cutting and having to build it up again or discard it.

In the safe position, the safety must engage the sear with zero clearance. The sear and hammer engage with 0.020 inches or less. If the thumb safety allows the sear to move at all when it’s engaged, it can make the trigger extremely light or worse, make the pistol fire immediately when the safety is disengaged. There are several places online to see an extensive safety testing procedure.

Besides very carefully stoning the safety lug, I had to remove a bit of metal so it could swing past the spring plunger housing.

I found the machined edges of the lever to be uncomfortably sharp against my thumb. I spent a bit of time melting some of the edges. The thing could use a lot of surface sanding before it gets refinished.

In any case, I’m pretty pleased with the functionality of both pieces. Now it just needs a range test and a bath.