Blueprint sets their engines up conservatively since they will be run under different conditions around the country. That means that the as delivered jetting tends to be on the rich side.
I have their 347 with the same carb, etc as yours. It also ran rich. Here's what I did.
1. Set the choke two notches lean from the "zero" position.
2. Jetted down 2 jet sizes
3. Idle screws set a 1-1/2 turns out from zero.
4. Installed spark plugs that are one heat range hotter. This means Champion C61YC or equal.
You also may find that you can advance the timing 2 to 4 degrees depending on the quality of the gas in your area.
I thought I would provide an update
1. I already had the choke set to where yours is set.
2. The documentation I found on the net indicated the 4160 carb comes with #64 main jets so I ordered 62's.They arrived today and I started replacing the jets. I soon found there were #66's in this carb so I had jets that are 4 sizes smaller.
Since I had it taken apart, I installed the #62's and went for a test drive. It stumbles when I accelerate so it looks like the #64's are what I need. I'll order those tonight.
3. I turned my idle screws in until the engine started to die, then backed them out 1/8 turn. They are now set to 1 full turn.
4. I'll be replacing the spark plugs tomorrow. I also pulled a plug and the outer rings is fouled but the tip is white. It looks like it had a .40 gap on it.
I checked the timing. With the vacuum advance plugged, it's at 12 degree BTDC. With vacuum, it looked to be 36 degrees. At idle, it makes 15 lbs of vacuum.