Barnyard is more of a fragment than a full song so I dont really have an issue with it though if it wasnt on the album it wouldnt be a major loss. A lot of those little fragments probably wouldnt have made the final cut of the record had it been finished back in the day. Or if they had they would have been fleshed out a bit more.
The one fragment I really wish had been fleshed out more was the original vocal melody for Do You Like Worms, which brian mumbles really quietly in the background on one of the sessions discs and it is a much cooler tune than the one they went with on BWPS.
I dont think any of the Smile boots had the extra chant until after the BWPS version. the chant was just one context-free fragment among many others so people didnt know what to do with it. Once brian put it back then everyone was like “oh yeah that works best” and pretty much every version that came after has it.
Surfs up just makes the most sense to close the album, it’s melancholy vibe is similar to “Caroline No” while also having a big climax and tying up a number of the albums themes. GV makes sense as the grand finale of a live show, and it’s perfectly good as a closer too. but hit singles generally arent album closers, so I think a hypothetical 60s version of the album would have it placed like it is on Smiley Smile as the side 2 opener.