I ran into some of these problems when doing mine as well, I ended pushing my engine back further into the firewall. I had to make dents with a hammer but the outcome of this was great. I was able to put the whole engine behind the front cross member, thus improving traction dramatically. This also allowed me to put the engine lower in the car, lower center of gravity. I used to run a 347 but am building a 408 turbo for it now. It is extremely easy to make engine mounts, for traction and trans position push the engine back into the fire wall as far as you can.
Adam