I'm surprised that 360's are so hard to find and expensive for you. They're not super common around here on craigslist, but the later trucks and vans still hit pickNpull frequently enough. I probably couldn't get one tomorrow or maybe even in a week or two, but I bet I could source one for under $300 in a month or so. I've paid as little as $50 for a 360, and that was a complete standard bore, original longblock. Granted that was 5 or 6 years ago, and was a bit of luck as I was there to buy other parts when it was offered to me.