At this point, restoring a GN doesn't make much sense. You will never recover the money you invest in it, vs. buying a low mileage, original.
You can still buy very low mileage cars for $14,000 (25K miles)
If you buy a 150K mile car for $6K or a rustbucket for $4K, you could very easily put $10K in paint, bodywork, engine rebuild, transmission, replacing broken and missing parts, etc. Now you have a 150K mile car with $14K in it.
The other drawback to building a car is you can't get your money out of it while you are building it. If something comes up and you have to sell your project before its finished, you get about 10 cents on the dollar for work and parts invested, because no one wants a 1/2 finished project. Everyone wants a low mileage T-R.
If you don't have enough money to buy a nice car, get a loan. Or, buy a 5.0 for $1500 and restore that. Sell it for $6K to a ricer when you are done and buy a T-R than needs that much less work.