Your problem is undoubtably affected by the bold fact that your car is not worth the value of what you wish to do to it. Thus your question more likely should be: how can I get my car back??
I would suggest getting a different car. If you have an attraction to the old iron, I would suggest a used motor. It may be possible for as little as $3k. These motors are virtually indestructable and I see beaters every day being scrapped with good motors. Unfortunately a simple head job on one will cost half the value of the car anymore.
We used to due an engine a week at one time. We now rebuild 2-4 a year. The cost now approaches the value of the car on almost every job we see.
BTW that $5k catalog motor will be at least $6.5k when you find a hole-in-the-wall that will install it. No professional I know will install someone else's rebuild and make no profit on the part. The warrantee risk is just TOO high. And don't tell me about releasing warrantee risk.
BTW I hope you aren't scrapping that motor because of a chain failure.
Bosch Master, ASE Master, L1
33 years MB technician