That wiring has obviously had some repair work done, but as long as it's feeding 12V to the positive coil terminal with the key in the run & crank positions, you can rule it out as the source of the no spark condition.
That engine will have points and a condenser located on top of the engine in a box right behind the carburetor. It will probably be the style where you have to remove a cover plate on the back side of the box to gain access to the points & condenser. I believe removing the battery will give you better access. Or if you're lucky it might have the type where you remove a single screw from the top and lift the cover off the points & condenser (that style gives you better access and is easier to adjust the points).
But with either style, you'll want to check the condition of the points, check the points gap (I think it's supposed to be 0.025" for the BF), and check the condition of the wire that connects them to the coil to make sure the insulation isn't damaged and shorting to ground where it passes out through the points box. Also, if you need to replace the condenser it doesn't necessarily have to be put back inside the box ... you can put it up near the coil and connect it to the negative terminal (just make sure it's securely mounted so it has a good ground).