Welcome aboard! And sweet looking truck! Here's my opinion on the engine...and you'll get a bunch of different answers, but take this from a guy who has fun with 6 cylinders.
The 350 is very common. TO common in my opinion. I skip over trucks that have that engine at car shows...just because I've seen it several to many times. Which means my stay is rather short. lol Its a darn good engine and has its reputation, BUT the 6 bangers have one just as good if not better.
That 230 properly tuned would get better mileage. But it really depends on what YOU want out of the truck. You trying to go the cheapest way possible not caring how common things are....350 will be the choice....though I highly doubt it will get much more mileage than the 230 would tuned up. You'd have more power though for sure...and P/s and A/C will be cheaper to setup. If you like things much more unique and different....I'd stick with the 230. Small mods can be done to tune these things up to run better. Just depends on how much you want to spend. To me its a shame to see a good running American engine dumped for a Japanese/Chinese crate engine. But that's my opinion. Whatever you decide we'll be here cheering you on. Good luck and I'm in for the build.
