I got my car registered last summer. I had to send my MSO and all the receipts to prove I built the car then they will send you a 90 day temp plate to drive the dar to the inspection - and anywhere else you want to go
Then I had to contact the NSRA to get the car inspected. The funny thing my 9 year old son realized was we had to drive the car 30 miles to meet the NSRA guy to get the saftey inspection done.
Common sense stuff but... Be sure your parking brake, lights and signals, and wipers work or you'll fail. You also can't have any steering linkage, fuel lines or cables below the frame scrub line or you'll fail.
The guy who inspected my car is a car guy and was really nice. The woman I spoke to in Springfield was pretty helpful although it took about 3-4 weeks.
Good luck
Nick