Unique 500+ Cubic Inch Engine Swap

[1972RedNeck]

The smog 350 in my '72 K20 is tired. It uses a lot of oil and is now burning water as well. Over the past two years I have been collecting parts for an engine swap. I want to go big - I don't care about fuel mileage for this truck, I just frame twisting, tire roasting low end torque with good mid range. The kind that makes it easy and fun to drive around town and can hook on a trailer and never look back.

Anyways, I have a couple of options. No matter what I do, I will either be keeping the 4 speed and swapping in 3.54 gears or leaving the 4.10's (with a heavier axle of course) and swapping in an NV4500 or the like.

Option number one that I have been leaning towards all along is a V6 GMC. I have all of the parts from a '68 GMC (Thanks Old_iron) so it would be a bolt in affair. I have a fresh 478M with a bad crank. Plan would be to offset grind the crank to fit BBC rods and custom pistons and cam to top it off. Should be in the 530 cubic inch range. Cost is going to be in the $4K range.

The other option that intrigues me is a 500 Cadillac. Can pickup a good runner for less than $500. It would take a flywheel and adapter plate from Cad Company and a simple cam swap to get it up to snuff. Cost would be in the $2500 range. If it ever had to be rebuilt, the crank would also get ground to BBC specs and would end up in the 530 cubic inch range...

Obviously the cost of the 500 is appealing, but I have always had a soft spot for big V6's as well.

What do you all say? Caddy is unique, but the V6 even more so...