Work with what you've got, unless you are on an unlimited budget. You can find a 302 at a later date and upgrade.
We did a father / son project when my kid was a teen. I was a little apprensive about putting lots of power in the car so we settled on a 243 ci inline. Now that he's grown up and a (slightly) more matured (40-something) he's getting a 305 ci six that should knock over a second off his quarter mile times.
The 243 gets re-purposed into one of Dad's lame projects.
