Subtle and submlime creativity is one of the things I enjoy about building these trucks and every other car I've built, including the diesels, 4s and 8s.
At the simplest end of the spectrum its figuring out that big block rod bolts are perfect replacements for the originals but only if you grind the heads down a little 'cause otherwise they hit the cam. Or that certain readily available valves fit just fine into these heads and with hardened seats work alot better with unleaded gasoline.
How and where am I going to mount that power steering pump when I've already got an alternator and a/c compressor on the driver side of the block, is a puzzler that I've enjoyed.
At the more complicated end, wondering if I can use the fuel injection set up and other stuff from the tried and true Jeep 4.0 inline six.
Building a 350 or other more common engines have their own problems, but most of them have been worked out by others and are available over the counter and ready made, which is great for other things, and the fun for me then is in other things.
That's just my two cents.
