The car is currently built solely for drag racing, and it get's very few miles on the road, so I'm thinking the solid mounts could be viable option. I'm more concerned about the engine twisting when accelerating, but let's see if that issue gets better with the new rubbers.
For racing only I would still use sone type of restraint on the lift of the driver side. Chain, steel strap or a factory had one already incorporated into the mount. I believe I seen them in vans. I broke a few before I learned, even new ones.