What class of vehicle do I register as, and what kind of inspections do I need to pass? 1970s drive train, so I guess 'street rod' unless that limits usage.
Look up the definitions and limitations of the available classes.
I considered registering my 58 as a "classic vehicle" because that reduced the fees by a lot, but that came with limitations in how much and for what purposes I am allowed to drive it.
One of my friends registered his as a commercial truck even though it cost more in fees because that exempted him from emissions checks.
At the end of the day, the best choice for you depends on how you want to use it.