Your gauges will work if you use the sending units from the 3.4: oil press, temp. Put them in the small block and plug into the stock harness.
As for a motor mount kit, go to the parts house and get the motor mounts for a small block 93 Camaro, pretty simple. Bolt em in, the chassis is already punched for them.
Your tach should work too, it will be the white wire paired with the thick pink wire going to your coil, unless it's DIS.
The stock speedo I'm not sure about, you'll need a converter first to take the cable speed from the trans and convert it to a electronic signal the speedo can use. Dakota digital makes different conversion setups for this, check with them.