shift it kind of slow and it will be ok. Avoid big shocks to the transmission.
I have a similar build (t5, 400+ hp 350cid, 2600 pounds) but also added a 200hp shot of n02. Car runs in the 10's and traps at 135 mph with slicks (1/4 mile).
The 5th gear is weak, avoid full power in 5th. (I broke my 5th gear).