This 263 was replacing a 248 in a '41.
It had two carbs and of course we wanted to keep them. We wanted to use the 263 motor mounts because it made for better balance and took a bunch of weight off the aluminum housed 5 speed. The good part is you can simply hang the motor and mounts on the engine, located it in the frame and bolt or weld them in place without spacers! But, when it came to mounting the dual carbs, there was an issue with clearance between the manifolds and the engine mount height. It had to be lowered.
We decided that if the engine mount sat about the center of the 4 bolt holes that there would be nice clearance and allow us to use the original 4 mounting holes. First step wack the engine mount side.
Here the mount is ready for tacking. There is no reason to turn the block part upside down, but I thought it might look better.
Here is the mount on the engine showing the clearance to the dual carburetor exhaust manifold.
After test fitting the exhaust tube, I decided to cut the shoulder off the mount to reduce interferance. At this point, I would choose to lower the mount another 1/4", or as close to the lower bolts as I could feel comfortable, to allow for more pipe clearance.