I think most often the reason that a turbo regal got put aside for years ( or a decade), is because it recieved a blown head gasket and was set aside to be fixed at a later date, and time went on and other things became more important ,money was better served elsewhere etc.
I would first be checking with stepdad to see if thats the case, If that is the case then don't crank it at all, tear it down or have it torn down to see exactly what you are dealing with, has water been sitting in a cyl or 2 or elsewhere in the motor for the last 10 years ?
If you are sure it wasn't a blown head gasket that caused it to be put on a shelf , i would still want to know the reason why it was ,to help determine the best course of action going forward.
Lots to do on a car that sat for 10 years before starting it,like all the usuals,drain the tank and clean it out,fresh gas,fresh oil and filter,new plugs etc.etc.you are going to want to be replacing all the vacuum hoses after it's running,after sitting outside for 10 yrs they are most likely dried out and will give you major head aches going forward.
If you end up dropping the tank to clean it,this would be the time to add a new fuel pump and hot wire kit, (especially if it is still the stock pump,) the stock pump was barely up to the task when new and now it is 30 years later.
It looks bone stock underhood How many miles on the car ?
If you are anywhere near someone that is VERY familiar with these cars and works on them, you would probably be MUCH better off spending the money and having them look at it ,assess the situation,and help you figure out what it needs and the best route forward.
But If you do decide to crank it , I would at least do the above mentioned things ,and pull the plugs and squirt some marvel mystery oil in the cylinders (not enough to hydraulic the motor)and let it soak into the rings/pistons for a day or two, just enough to free up any stuck rings etc. and give it some kind of lube between the cyl walls and piston rings and help dissolve and lube over any rust in the cylinders.
http://www.marvelmysteryoil.com/index.php/site/universallp
I would also do the initial cranking without starting it,unhook the orange wire near the battery and it shouldn't want to start , though i have heard of people's that would start even with that unhooked for some reason.
I don't know if you would lose prime on the oil pump after sitting so long ( Iwouldn't think so ) but watch for oil pressure ,better safe then sorry, any of the guru's could answer this priming question.
Again i would suggest having someone Very versed in Turbo Regal-ology there to help you assess the situation.
If you bring it to your local garage they will probably mess it up and cause more problems then they fix.
These cars really need someone who is very familiar with their unique set of intricacies,15+ lbs of boost will find any weaknesses , mistakes, or shortcomings pretty quick.
If you get it running/driving don't get into boost until you know you have it running 100 percent.
These cars can self destruct pretty quick under boost if things are not right, and after sitting 10 yrs there is probably alot thats not right.
You should invest in a scan master and learn how to read it, do alot of reading of past threads ,and ask lots of questions here,there is alot of very knowledgable people ready to help that can save you alot of money and head aches in the future.
Good luck with the new project.