dont spend more than $500 on a vk commodore with a vl engine in it.
my 2c, and although you may love the car, you WILL regret doing it in the future..... (but hey, if i had 20gs what i would do with it would be considered a waste by someone else) Also, once you have spent the money on it, and done everything to the old vk that you possibly can do, maybe even been defected a few times, then you want to sell and upgrade, you will struggle finding someone to buy it for more than $5000 if that.
In reality, a $1500 car with $15,000 of work more often than not, doesnt compare to a $16500 car.