Airflow
You will not need to beef up your internals at all to accept the new heads, intake, and cams. The only thing you may consider improving at the same time is the valve springs. With a more radical lobed cam you will see valve float at higher RPM's, if you went with a mild cam you should be fine as you are.
The internals would, however, be a vital stage in the buildup of a reliable blower motor. Although you can run around 8psi to a stock 2v block, there is never any guaruntee on how long your engine will last. With MPH's Mongoose Kit and the tune by Tim many people seem to be seeing a very reliable engine, even when all else is bone stock. But heh, if you have the loot, and/or the patience, build it right with some forged goodies.
I am most likely going to be doing the Paxton kit from MPH, but I don't have the loot, or the patience, to wait for forged internals, those will come a little later. I'll be picking up a Lightning at the same time, so the internals have to wait a bit.
