The stock Delco Remy distributors were made of excellent materials. The 2403 is the correct application for the 1960 motor. You need a vacuum advance for a street driven vehicle so take the time to get it all installed.
No sense in trying to reengineer what the engineers have already long ago sorted out.
You will want to take the 2403 apart, including removal of the point plate, and degrease everything. If the mechanical weights are rusty, you will need to disassemble the weights, wire brush them up nice and smooth, lubricate and reinstall. Make sure the two advance spring posts are tight and the springs are intact. Make sure the lobes are clean and smooth. Install the point plate and a decent set of Lubriplate points, new condenser (or one of the spiffy replacements one of our members sells). I think you will find yourself much better served with a clean, adjusted 2403 distributor, with a working vacuum advance.
Now, dual points. Dual points were the bomb when I was in high school in the 70s and earlier. One of the reasons, there were really not that many alternatives, especially for the 235/261. The dual points were intended to increase saturation time and theoretically work better. And they did work to a degree in higher rpm motors. Since that time, lots of better alternatives, HEI, MSD. But for a stock motor, I would venture a guess that there is little to no real improvement in a stock motor by using a dual point distributor.
I have one of those distributors, brand new. And the truth is I have never installed it and I would be hesitant to install it on a stock motor, or even a higher performance 235 or 261 over say a 2304 distributor and an MSD, or even just a stock 2403.
Just as an example, I ran one of my modified 261 motors down Beach Bend Raceway in 2015 and 2016, getting in the range of 5800 rpm with a rebuilt 2403 and a set of lubripoints and that motor did not skip a beat.
The other thing is parts. Cap, rotor, points, all pretty easy to get for the 2403 distributor, and not all that expensive. The Mallory, not so much.
