[AzCal Retred]

The "Word" from The Man! 

https://www.cycleworld.com/everything-youve-ever-wanted-to-know-about-aluminum/

https://www.cycleworld.com/story/blogs/ask-kevin/how-cast-aluminum-chassis-became-possible/

http://www.r-r-racing.com/HD%20frame%20page.htm
"Aluminum Hardtail Frames Starting at $1400"

Seems like with a UCE motor in one of these alloy frames, and with alloy rims, you could be looking at a 325 pound or so road burner. Losing 75-100 pounds is like gaining horsepower, plus the chiropractic bills go down. RRR Racing could likely whomp up one for maybe $2K-ish?

[Karl Childers]

While familiar with alloy perimeter frames that's the first I've seen tube frames done up in it. Harley has never been too concerned with the weight of their motorcycles so an alloy frame is only going to pay so many dividends, I can definitely see the advantage for other sportier classic bikes. 

[AzCal Retred]

The UCE engine should be "lighter per HP" than a Pre-Unit assembly, if engineering runs true to form. Either would be interesting in an alloy frame. Less Weight = more better!