Chassis Engineering (now owned by Heidt's) has mounts for just about any swap and used to offer them in either bolt in or weld in. By far the easiest is the ones that use a bracket that bolts to the engine and the frame bracket either bolts or welds to the frame. These take the Flathead Ford mount biscuits and are super stable plus you will love being able to set the engine straight down onto the cushions rather than fight angled mounts. With the torque of a big block one might use the tube that runs from frame rail to frame rail and has the brackets to take the factory mount cushions. We don't use this set up often because the tube is in the way of everything. If you do a search on "Chassis Engineering Motor Mounts" many are listed but I would call them and tell what you are doing.

Evan