I believe the OP is looking to build a 1911.
The STI Short Block Kit is a 2011.
STI offers a 1911 frame with pre-fit slide and frame. According to the description it's for a .45 ACP non-ramped barrel. I may be wrong but I don't think STI offers a 1911 frame with pre-fit slide and frame for a ramped barrel.
I'm a big fan of STI and own several, but those Fusion kits look like a hell of a deal.
Marv Z: If you're looking at the Fusion Scout Kit with the barrel already fit and the plunger tube installed I agree with raz-0, you're looking at fitting the parts he listed. If you feel comfortable doing that level of work you should have no problem with the Fusion Scout Kit.
Beyond that you need to decide what level of cosmetic work you want to do. I like to blend the grip safety to the back of the frame and blend the MSH to the frame. I'm not familiar with the bare STI/Fusion frame but a Caspian frame benefits from some smoothing and blending in the trigger guard area. I also like to break all of the sharp edges and smooth them out. Kind of like a carry bevel but almost imperceptible where you really have to look to see that it's been done.
Good luck!
Rick
Back of slide and frame blended after barrel was fit. Grip safety blended to frame.
Funky lighting, the colors of the various parts do match.
Trigger guard on Caspian frame.